Fix wrong type hints in data_files

Fix wrong type hints in data_files introduced in:
- #6493

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_6910). 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) | 0.005135 / 0.011353 (-0.006218) | 0.003757 / 0.011008 (-0.007251) | 0.063122 / 0.038508 (0.024614) | 0.029837 / 0.023109 (0.006727) | 0.246120 / 0.275898 (-0.029778) | 0.268529 / 0.323480 (-0.054951) | 0.004136 / 0.007986 (-0.003849) | 0.002650 / 0.004328 (-0.001678) | 0.048749 / 0.004250 (0.044499) | 0.045279 / 0.037052 (0.008226) | 0.257970 / 0.258489 (-0.000519) | 0.285993 / 0.293841 (-0.007848) | 0.027612 / 0.128546 (-0.100935) | 0.010175 / 0.075646 (-0.065471) | 0.207373 / 0.419271 (-0.211899) | 0.037672 / 0.043533 (-0.005861) | 0.249603 / 0.255139 (-0.005536) | 0.271081 / 0.283200 (-0.012119) | 0.018174 / 0.141683 (-0.123509) | 1.116703 / 1.452155 (-0.335452) | 1.169261 / 1.492716 (-0.323455) |

### 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) | 0.095161 / 0.018006 (0.077155) | 0.301112 / 0.000490 (0.300623) | 0.000221 / 0.000200 (0.000021) | 0.000042 / 0.000054 (-0.000012) |

### Benchmark: benchmark_indices_mapping.json

| metric | select | shard | shuffle | sort | train_test_split |
|--------|---|---|---|---|---|
| new / old (diff) | 0.023218 / 0.037411 (-0.014193) | 0.063125 / 0.014526 (0.048599) | 0.075857 / 0.176557 (-0.100699) | 0.137922 / 0.737135 (-0.599213) | 0.076989 / 0.296338 (-0.219349) |

### 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) | 0.279272 / 0.215209 (0.064063) | 2.776463 / 2.077655 (0.698809) | 1.472220 / 1.504120 (-0.031900) | 1.347105 / 1.541195 (-0.194090) | 1.361014 / 1.468490 (-0.107476) | 0.589233 / 4.584777 (-3.995544) | 2.395212 / 3.745712 (-1.350500) | 2.794855 / 5.269862 (-2.475007) | 1.698350 / 4.565676 (-2.867327) | 0.063328 / 0.424275 (-0.360947) | 0.005020 / 0.007607 (-0.002588) | 0.335872 / 0.226044 (0.109828) | 3.293486 / 2.268929 (1.024558) | 1.837270 / 55.444624 (-53.607354) | 1.535694 / 6.876477 (-5.340782) | 1.559696 / 2.142072 (-0.582376) | 0.639302 / 4.805227 (-4.165925) | 0.116554 / 6.500664 (-6.384110) | 0.042305 / 0.075469 (-0.033164) |

### 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) | 0.971562 / 1.841788 (-0.870226) | 11.710500 / 8.074308 (3.636192) | 9.505935 / 10.191392 (-0.685457) | 0.139161 / 0.680424 (-0.541263) | 0.014351 / 0.534201 (-0.519850) | 0.285790 / 0.579283 (-0.293493) | 0.265718 / 0.434364 (-0.168646) | 0.323558 / 0.540337 (-0.216780) | 0.412635 / 1.386936 (-0.974301) |

</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) | 0.005987 / 0.011353 (-0.005366) | 0.003787 / 0.011008 (-0.007221) | 0.049839 / 0.038508 (0.011331) | 0.032817 / 0.023109 (0.009708) | 0.268304 / 0.275898 (-0.007594) | 0.303409 / 0.323480 (-0.020071) | 0.004924 / 0.007986 (-0.003061) | 0.002740 / 0.004328 (-0.001589) | 0.048906 / 0.004250 (0.044655) | 0.044266 / 0.037052 (0.007213) | 0.290506 / 0.258489 (0.032017) | 0.314124 / 0.293841 (0.020283) | 0.030242 / 0.128546 (-0.098304) | 0.010555 / 0.075646 (-0.065091) | 0.058849 / 0.419271 (-0.360423) | 0.033540 / 0.043533 (-0.009993) | 0.267833 / 0.255139 (0.012694) | 0.291056 / 0.283200 (0.007857) | 0.018611 / 0.141683 (-0.123072) | 1.137620 / 1.452155 (-0.314534) | 1.199554 / 1.492716 (-0.293162) |

### 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) | 0.096716 / 0.018006 (0.078709) | 0.302033 / 0.000490 (0.301543) | 0.000217 / 0.000200 (0.000017) | 0.000044 / 0.000054 (-0.000010) |

### Benchmark: benchmark_indices_mapping.json

| metric | select | shard | shuffle | sort | train_test_split |
|--------|---|---|---|---|---|
| new / old (diff) | 0.023208 / 0.037411 (-0.014203) | 0.076231 / 0.014526 (0.061705) | 0.088672 / 0.176557 (-0.087884) | 0.129033 / 0.737135 (-0.608103) | 0.090709 / 0.296338 (-0.205630) |

### 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) | 0.297033 / 0.215209 (0.081824) | 2.951181 / 2.077655 (0.873526) | 1.567690 / 1.504120 (0.063570) | 1.436809 / 1.541195 (-0.104385) | 1.469696 / 1.468490 (0.001206) | 0.567963 / 4.584777 (-4.016813) | 0.954168 / 3.745712 (-2.791544) | 2.700473 / 5.269862 (-2.569389) | 1.742144 / 4.565676 (-2.823532) | 0.065027 / 0.424275 (-0.359248) | 0.005319 / 0.007607 (-0.002288) | 0.346459 / 0.226044 (0.120415) | 3.446117 / 2.268929 (1.177189) | 1.953142 / 55.444624 (-53.491483) | 1.639131 / 6.876477 (-5.237346) | 1.830664 / 2.142072 (-0.311409) | 0.657807 / 4.805227 (-4.147420) | 0.117987 / 6.500664 (-6.382678) | 0.040726 / 0.075469 (-0.034744) |

### 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) | 0.992666 / 1.841788 (-0.849122) | 12.305377 / 8.074308 (4.231069) | 10.274829 / 10.191392 (0.083437) | 0.141731 / 0.680424 (-0.538692) | 0.015100 / 0.534201 (-0.519101) | 0.282298 / 0.579283 (-0.296985) | 0.124301 / 0.434364 (-0.310063) | 0.320914 / 0.540337 (-0.219424) | 0.445855 / 1.386936 (-0.941081) |

</details>
</details>

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