remove two deprecated function
Author: ji-huazhong
Pull request: yes

# What does this PR do?

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we are now at 4.37.0.dev0, it's time to say goodbye to `torch_required` and `tf_required`


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cc @ydshieh 

Comments:
Hi @statelesshz Thanks a lot for this PR! Let's wait a bit the response from #25948 🙏 

@ydshieh 
Thanks for the notification.

This is handled by someone else currently, so I don't hold strong opinion against it.
My understanding is if there's breaking change they'll likely to pin down version instead of patching.

However all previous points regarding API stability still holds.
It'll unavoidably break a lot of existing community code, without clear benefit.
It there's any strong benefit I missed, please state that in PR desc.

The points are valid, but I am not sure about ` break a lot of existing community code`.

Keep something in the codebase we don't use anymore is not great. Having it in a legacy dir is only worth it if that code is really used in the wild (for which I am not sure it's the case). Keep it with a warning is also not ideal - we have a lot of discussion about if to keep warnings or not etc.

I will move on - and if we eventually see it is indeed used a lot by the community, we can put it back (but in a legacy dir).

> Keep something in the codebase we don't use anymore is not great

Agree

> Having it in a legacy dir is only worth it if that code is really used in the wild (for which I am not sure it's the case)

`@torch_required` is currently used by 704 files just on GitHub:
- https://github.com/search?q=%40torch_required&type=code

![image](https://github.com/huggingface/transformers/assets/5203025/ea661c53-5fb7-451d-bd3d-94878786ffd7)

66 files for `@tf_required`:
- https://github.com/search?q=%40tf_required&type=code


Thanks a lot for this information!

But some (if not many) of them are actually including the definitions of those 2 functions in a file in their own repository.