delete the hardcoded license list in `datasets`
> Feel free to delete the license list in `datasets` [...]
>
> Also FYI in #4926 I also removed all the validation steps anyway (language, license, types etc.)

_Originally posted by @lhoestq in https://github.com/huggingface/datasets/issues/4930#issuecomment-1238401662_

> [...], in my opinion we can just delete this file from `datasets`, the validation is happening hub-side anyways now?

_Originally posted by @julien-c in https://github.com/huggingface/datasets/issues/4930#issuecomment-1238390659_