[finetune_trainer] enhancements and fixes (#9042)
* trainer and finetune_trainer enhancements and fixes
* add fallback default
* move the fixing of incorrect keys back into finetune trainer
* s/eval/val/ to match the split
* trainer can now use a different prefix than eval_ for metrics
* document new arg
* Apply suggestions from code review
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
* use 'eval' as the default for metric_key_prefix
* complete adjust var names + disambiguate
* fix logger
* add clarifying comment
* add clarifying comment
* style
* Apply suggestions from code review
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
* Update src/transformers/trainer.py
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
* complete removal of optional for metric_key_prefix
* Apply suggestions from code review
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
