[from_pretrained] Simpler code for peft

[ArthurZucker]

What does this PR do?

Simplifies the logic when loading a PEFT model: the _adapter_model_path is used instead of maybe_has_adapter_model_path and has_adapter_config

[sgugger]

Looks simpler indeed!

[HuggingFaceDocBuilderDev]

The documentation is not available anymore as the PR was closed or merged.

[younesbelkada]

Thanks a lot @ArthurZucker for attempting to refactor that part, sadly all PEFT tests are failing with your changes, can you please make sure they pass before merging?

RUN_SLOW=1 pytest tests/peft_integration/test_peft_integration.py

Also make sure to rebase with main in order to run the tests

I suspect the reason is because you need to override the pretrained_model_name_or_path instance with _adapter_model_path and store the current adapter id in a new variable adapter_model_id in the previous changes

[ArthurZucker]

Thanks! Can confirm that the tests are now green! @younesbelkada some are really fast do you not want to remove the slow mention for them?

[younesbelkada]

Thanks! All of them should be using tiny models so they are fast, I don't know if we want to add PEFT as a dependency to our CIs so maybe let's keep it as it is for now, what do you think?

[younesbelkada]

@ArthurZucker sorry the tests are still failing, probably something wrong happened during the merge, can you double check? 🙏 I can also have a look if you want

Edit: just made #25733