Fix StopStringCriteria to handle tokens above len(tokenizer) (#35797)
* Fix StopStringCriteria to handle tokens above len(tokenizer)
This fixes #35244 by clipping token IDs to be within the tokenizer's vocabulary size before performing the embedding lookup. This prevents index errors when model.config.vocab_size > len(tokenizer).
The fix:
1. Adds a clamp operation to ensure token IDs are within bounds
2. Adds a test case to verify the behavior
* Use self.stop_strings instead of stop_strings
* Handle clipping correctly
* make fixup
* Update test to the new embedding vecs
* Use much bigger values in the mismatch test
* Typo fix
* Slight simplification
---------
Co-authored-by: openhands <openhands@all-hands.dev>