can't set verbosity for `metric.py`
Thanks @thomas-happify for reporting and thanks @mariosasko for the fix.
## Describe the bug
```
[2021-07-10 20:13:11,528][datasets.utils.filelock][INFO] - Lock 139705371374976 acquired on /root/.cache/huggingface/metrics/seqeval/default/default_experiment-1-0.arrow.lock
[2021-07-10 20:13:11,529][datasets.arrow_writer][INFO] - Done writing 32 examples in 6100 bytes /root/.cache/huggingface/metrics/seqeval/default/default_experiment-1-0.arrow.
[2021-07-10 20:13:11,531][datasets.arrow_dataset][INFO] - Set __getitem__(key) output type to python objects for no columns  (when key is int or slice) and don't output other (un-formatted) columns.
[2021-07-10 20:13:11,543][/conda/envs/myenv/lib/python3.8/site-packages/datasets/metric.py][INFO] - Removing /root/.cache/huggingface/metrics/seqeval/default/default_experiment-1-0.arrow
```
As you can see, `datasets` logging come from different places. 
`filelock`, `arrow_writer` & `arrow_dataset` comes from `datasets.*` which are expected 
However, `metric.py` logging comes from `/conda/envs/myenv/lib/python3.8/site-packages/datasets/`

So when setting `datasets.utils.logging.set_verbosity_error()`,  it still logs the last message which is annoying during evaluation. 

I had to do 
```
logging.getLogger("/conda/envs/myenv/lib/python3.8/site-packages/datasets/metric").setLevel(logging.ERROR)
``` 
to fully mute these messages

## Expected results
it shouldn't log these messages when setting `datasets.utils.logging.set_verbosity_error()`

## Environment info
<!-- You can run the command `datasets-cli env` and copy-and-paste its output below. -->
- `datasets` version: tried both 1.8.0 & 1.9.0
- Platform: Ubuntu 18.04.5 LTS 
- Python version: 3.8.10
- PyArrow version: 3.0.0
