"no-token" is passed to `huggingface_hub` when token is `None`
## Describe the bug

In the 2 lines listed below, a token is passed to `huggingface_hub` to get information from a dataset. If no token is provided, a "no-token" string is passed. What is the purpose of it ? If no real, I would prefer if the `None` value could be sent directly to be handle by `huggingface_hub`. I feel that here it is working because we assume the token will never be validated.

https://github.com/huggingface/datasets/blob/5b23f58535f14cc4dd7649485bce1ccc836e7bca/src/datasets/load.py#L753
https://github.com/huggingface/datasets/blob/5b23f58535f14cc4dd7649485bce1ccc836e7bca/src/datasets/load.py#L1121

## Expected results
Pass `token=None` to `huggingface_hub`.

## Actual results
`token="no-token"` is passed.

## Environment info
`huggingface_hub v0.10.0dev`