Saving `Trainer.collator.tokenizer` in when `Trainer.processing_class` is `None` (#36552)
* feat: Saving tokenizer in collator when processing_class is None
* chore: Style issue
* chore: Typo
* dbg: Check why test failed
* dbg: Remove logics and another test failed which successed before, so should be the stablibility issue
* test: Init unit-test
* chore: Style
* chore: Add err log
* fix: Case
* Update tests/trainer/test_trainer.py
Co-authored-by: Marc Sun <57196510+SunMarc@users.noreply.github.com>
* chore: Try to use get_regression_trainer
* fix: Impl and style
* fix: Style
* fix: Case
* fix: Import err
* fix: Missed import
* fix: Import block un-sorted problem
* fix: Try another tokenizer
* fix: Test logic
* chore: Light updates
* chore: Reformat
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Co-authored-by: Marc Sun <57196510+SunMarc@users.noreply.github.com>