PEFT / Trainer: Make use of `model.active_adapters()` instead of deprecated `model.active_adapter` whenever possible (#30738)
* Update trainer.py
* Update src/transformers/trainer.py
* Update src/transformers/trainer.py
* Update src/transformers/trainer.py
* style
* Update src/transformers/trainer.py
* Update src/transformers/trainer.py