[Deprecation] Remove prompt_token_ids arg fallback in LLM.generate and LLM.embed

[DarkLight1337]

First introduced all the way back in #4328, with deprecation flag turned on in #11129. This should be safe to remove.

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[DarkLight1337]

Looks like lm_eval still uses the deprecated parameter prompt_token_ids. Let me open an issue on their end.

Edit: Opened EleutherAI/lm-evaluation-harness#3024

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @DarkLight1337.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork