Fix tests using hf-internal-testing/librispeech_asr_dummy

Fix tests using hf-internal-testing/librispeech_asr_dummy once that dataset has been converted to Parquet.

Fix #6997.

Comments:
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_6998). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

<details>
<summary>Show benchmarks</summary>

PyArrow==8.0.0

<details>
<summary>Show updated benchmarks!</summary>

### Benchmark: benchmark_array_xd.json

| metric | read_batch_formatted_as_numpy after write_array2d | read_batch_formatted_as_numpy after write_flattened_sequence | read_batch_formatted_as_numpy after write_nested_sequence | read_batch_unformated after write_array2d | read_batch_unformated after write_flattened_sequence | read_batch_unformated after write_nested_sequence | read_col_formatted_as_numpy after write_array2d | read_col_formatted_as_numpy after write_flattened_sequence | read_col_formatted_as_numpy after write_nested_sequence | read_col_unformated after write_array2d | read_col_unformated after write_flattened_sequence | read_col_unformated after write_nested_sequence | read_formatted_as_numpy after write_array2d | read_formatted_as_numpy after write_flattened_sequence | read_formatted_as_numpy after write_nested_sequence | read_unformated after write_array2d | read_unformated after write_flattened_sequence | read_unformated after write_nested_sequence | write_array2d | write_flattened_sequence | write_nested_sequence |
|--------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| new / old (diff) | 0.005396 / 0.011353 (-0.005957) | 0.003974 / 0.011008 (-0.007034) | 0.063490 / 0.038508 (0.024982) | 0.030299 / 0.023109 (0.007189) | 0.244489 / 0.275898 (-0.031409) | 0.274116 / 0.323480 (-0.049364) | 0.003187 / 0.007986 (-0.004798) | 0.003433 / 0.004328 (-0.000896) | 0.049313 / 0.004250 (0.045062) | 0.043677 / 0.037052 (0.006624) | 0.260198 / 0.258489 (0.001709) | 0.283558 / 0.293841 (-0.010283) | 0.029728 / 0.128546 (-0.098819) | 0.011950 / 0.075646 (-0.063696) | 0.204371 / 0.419271 (-0.214901) | 0.035712 / 0.043533 (-0.007821) | 0.252715 / 0.255139 (-0.002424) | 0.268906 / 0.283200 (-0.014293) | 0.021153 / 0.141683 (-0.120529) | 1.125599 / 1.452155 (-0.326556) | 1.163122 / 1.492716 (-0.329594) |

### Benchmark: benchmark_getitem\_100B.json

| metric | get_batch_of\_1024\_random_rows | get_batch_of\_1024\_rows | get_first_row | get_last_row |
|--------|---|---|---|---|
| new / old (diff) | 0.095089 / 0.018006 (0.077083) | 0.298576 / 0.000490 (0.298086) | 0.000214 / 0.000200 (0.000014) | 0.000051 / 0.000054 (-0.000004) |

### Benchmark: benchmark_indices_mapping.json

| metric | select | shard | shuffle | sort | train_test_split |
|--------|---|---|---|---|---|
| new / old (diff) | 0.018567 / 0.037411 (-0.018844) | 0.062337 / 0.014526 (0.047811) | 0.074231 / 0.176557 (-0.102326) | 0.120960 / 0.737135 (-0.616175) | 0.076124 / 0.296338 (-0.220215) |

### Benchmark: benchmark_iterating.json

| metric | read 5000 | read 50000 | read_batch 50000 10 | read_batch 50000 100 | read_batch 50000 1000 | read_formatted numpy 5000 | read_formatted pandas 5000 | read_formatted tensorflow 5000 | read_formatted torch 5000 | read_formatted_batch numpy 5000 10 | read_formatted_batch numpy 5000 1000 | shuffled read 5000 | shuffled read 50000 | shuffled read_batch 50000 10 | shuffled read_batch 50000 100 | shuffled read_batch 50000 1000 | shuffled read_formatted numpy 5000 | shuffled read_formatted_batch numpy 5000 10 | shuffled read_formatted_batch numpy 5000 1000 |
|--------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| new / old (diff) | 0.286936 / 0.215209 (0.071727) | 2.816656 / 2.077655 (0.739001) | 1.486772 / 1.504120 (-0.017348) | 1.373289 / 1.541195 (-0.167905) | 1.392739 / 1.468490 (-0.075752) | 0.708091 / 4.584777 (-3.876686) | 2.410034 / 3.745712 (-1.335678) | 2.912701 / 5.269862 (-2.357161) | 1.850924 / 4.565676 (-2.714752) | 0.078896 / 0.424275 (-0.345380) | 0.005116 / 0.007607 (-0.002491) | 0.332275 / 0.226044 (0.106231) | 3.306562 / 2.268929 (1.037633) | 1.853051 / 55.444624 (-53.591573) | 1.556210 / 6.876477 (-5.320267) | 1.558892 / 2.142072 (-0.583181) | 0.789917 / 4.805227 (-4.015310) | 0.133683 / 6.500664 (-6.366981) | 0.042566 / 0.075469 (-0.032904) |

### Benchmark: benchmark_map_filter.json

| metric | filter | map fast-tokenizer batched | map identity | map identity batched | map no-op batched | map no-op batched numpy | map no-op batched pandas | map no-op batched pytorch | map no-op batched tensorflow |
|--------|---|---|---|---|---|---|---|---|---|
| new / old (diff) | 0.957050 / 1.841788 (-0.884738) | 11.401462 / 8.074308 (3.327154) | 9.782988 / 10.191392 (-0.408404) | 0.142127 / 0.680424 (-0.538296) | 0.014730 / 0.534201 (-0.519471) | 0.302647 / 0.579283 (-0.276636) | 0.264654 / 0.434364 (-0.169710) | 0.341340 / 0.540337 (-0.198998) | 0.425808 / 1.386936 (-0.961128) |

</details>
PyArrow==latest

<details>
<summary>Show updated benchmarks!</summary>

### Benchmark: benchmark_array_xd.json

| metric | read_batch_formatted_as_numpy after write_array2d | read_batch_formatted_as_numpy after write_flattened_sequence | read_batch_formatted_as_numpy after write_nested_sequence | read_batch_unformated after write_array2d | read_batch_unformated after write_flattened_sequence | read_batch_unformated after write_nested_sequence | read_col_formatted_as_numpy after write_array2d | read_col_formatted_as_numpy after write_flattened_sequence | read_col_formatted_as_numpy after write_nested_sequence | read_col_unformated after write_array2d | read_col_unformated after write_flattened_sequence | read_col_unformated after write_nested_sequence | read_formatted_as_numpy after write_array2d | read_formatted_as_numpy after write_flattened_sequence | read_formatted_as_numpy after write_nested_sequence | read_unformated after write_array2d | read_unformated after write_flattened_sequence | read_unformated after write_nested_sequence | write_array2d | write_flattened_sequence | write_nested_sequence |
|--------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| new / old (diff) | 0.005679 / 0.011353 (-0.005674) | 0.003513 / 0.011008 (-0.007495) | 0.050135 / 0.038508 (0.011627) | 0.031614 / 0.023109 (0.008505) | 0.260064 / 0.275898 (-0.015834) | 0.285816 / 0.323480 (-0.037664) | 0.004428 / 0.007986 (-0.003558) | 0.002816 / 0.004328 (-0.001512) | 0.048441 / 0.004250 (0.044191) | 0.039622 / 0.037052 (0.002570) | 0.274940 / 0.258489 (0.016451) | 0.311837 / 0.293841 (0.017996) | 0.031439 / 0.128546 (-0.097107) | 0.012056 / 0.075646 (-0.063590) | 0.060109 / 0.419271 (-0.359163) | 0.033123 / 0.043533 (-0.010409) | 0.261563 / 0.255139 (0.006424) | 0.282640 / 0.283200 (-0.000560) | 0.017168 / 0.141683 (-0.124515) | 1.127859 / 1.452155 (-0.324295) | 1.182414 / 1.492716 (-0.310303) |

### Benchmark: benchmark_getitem\_100B.json

| metric | get_batch_of\_1024\_random_rows | get_batch_of\_1024\_rows | get_first_row | get_last_row |
|--------|---|---|---|---|
| new / old (diff) | 0.095517 / 0.018006 (0.077510) | 0.300578 / 0.000490 (0.300088) | 0.000212 / 0.000200 (0.000012) | 0.000044 / 0.000054 (-0.000010) |

### Benchmark: benchmark_indices_mapping.json

| metric | select | shard | shuffle | sort | train_test_split |
|--------|---|---|---|---|---|
| new / old (diff) | 0.022192 / 0.037411 (-0.015220) | 0.076617 / 0.014526 (0.062091) | 0.087405 / 0.176557 (-0.089151) | 0.127011 / 0.737135 (-0.610124) | 0.088706 / 0.296338 (-0.207632) |

### Benchmark: benchmark_iterating.json

| metric | read 5000 | read 50000 | read_batch 50000 10 | read_batch 50000 100 | read_batch 50000 1000 | read_formatted numpy 5000 | read_formatted pandas 5000 | read_formatted tensorflow 5000 | read_formatted torch 5000 | read_formatted_batch numpy 5000 10 | read_formatted_batch numpy 5000 1000 | shuffled read 5000 | shuffled read 50000 | shuffled read_batch 50000 10 | shuffled read_batch 50000 100 | shuffled read_batch 50000 1000 | shuffled read_formatted numpy 5000 | shuffled read_formatted_batch numpy 5000 10 | shuffled read_formatted_batch numpy 5000 1000 |
|--------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| new / old (diff) | 0.294260 / 0.215209 (0.079051) | 2.872879 / 2.077655 (0.795224) | 1.531374 / 1.504120 (0.027254) | 1.399232 / 1.541195 (-0.141962) | 1.400708 / 1.468490 (-0.067782) | 0.714003 / 4.584777 (-3.870773) | 0.943144 / 3.745712 (-2.802568) | 2.833396 / 5.269862 (-2.436466) | 1.890570 / 4.565676 (-2.675106) | 0.077664 / 0.424275 (-0.346611) | 0.005651 / 0.007607 (-0.001956) | 0.349476 / 0.226044 (0.123431) | 3.405768 / 2.268929 (1.136840) | 1.869739 / 55.444624 (-53.574885) | 1.575293 / 6.876477 (-5.301184) | 1.692981 / 2.142072 (-0.449092) | 0.795363 / 4.805227 (-4.009865) | 0.131532 / 6.500664 (-6.369132) | 0.041183 / 0.075469 (-0.034286) |

### Benchmark: benchmark_map_filter.json

| metric | filter | map fast-tokenizer batched | map identity | map identity batched | map no-op batched | map no-op batched numpy | map no-op batched pandas | map no-op batched pytorch | map no-op batched tensorflow |
|--------|---|---|---|---|---|---|---|---|---|
| new / old (diff) | 1.000821 / 1.841788 (-0.840967) | 11.987795 / 8.074308 (3.913487) | 10.147652 / 10.191392 (-0.043740) | 0.141314 / 0.680424 (-0.539110) | 0.015506 / 0.534201 (-0.518695) | 0.305090 / 0.579283 (-0.274193) | 0.123403 / 0.434364 (-0.310960) | 0.346507 / 0.540337 (-0.193831) | 0.471318 / 1.386936 (-0.915618) |

</details>
</details>

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