Make `get_special_tokens_mask` consider all tokens
# What does this PR do?

As discovered via #11155, some tokenizers do not return the proper special tokens mask in the `get_special_tokens_mask` when `already_has_special_tokens=True` because they only check for the CLS and SEP tokens. This PR fixes that by delegating to the superclass the call when `already_has_special_tokens=True` (the generic method checks for all special tokens).

It also seems from the error message [here](https://github.com/huggingface/transformers/blob/b9b60c1630f63b54b10380ef8bf30ec323985553/src/transformers/tokenization_utils_base.py#L3091) that the `get_special_tokens_mask` method is not supposed to be implemented for fast tokenziers when `already_has_special_tokens=True`, so this PR removes this method from the fast tokenizers where it exists, except for a select few that have a different implementation.

Fixes #11155
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