Remove text_generation.py (vllm-project#1793)

SUMMARY:
- We've had multiple releases indicating this will be removed
- Docs will still indicate that this has been removed but I think we're
ok to remove from codebase given we've updated all examples as well

Author: dsikka

src/llmcompressor/transformers/finetune/__init__.py

@@ -2,4 +2,3 @@
 
 from .data import TextGenerationDataset
 from .session_mixin import SessionManagerMixIn
-from .text_generation import apply, oneshot, train