Update config validation

[Manalelaidouni]

What does this PR do?

Fixes #33690

This PR adds extra validation for generation parameters to fail early when invalid values are passed and not let things fail silently as suggested in the issue.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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• Did you write any new necessary tests?

Who can review?

@gante @zucchini-nlp