Just import torch AdamW instead (#36177)

* Just import torch AdamW instead

* Update docs too

* Make AdamW undocumented

* make fixup

* Add a basic wrapper class

* Add it back to the docs

* Just remove AdamW entirely

* Remove some AdamW references

* Drop AdamW from the public init

* make fix-copies

* Cleanup some references

* make fixup

* Delete lots of transformers.AdamW references

* Remove extra references to adamw_hf

tests/trainer/test_trainer.py

@@ -5375,16 +5375,6 @@ if is_torch_available():
     }
 
     optim_test_params = [
-        (
-            OptimizerNames.ADAMW_HF,
-            transformers.optimization.AdamW,
-            default_adam_kwargs,
-        ),
-        (
-            OptimizerNames.ADAMW_HF.value,
-            transformers.optimization.AdamW,
-            default_adam_kwargs,
-        ),
         (
             OptimizerNames.ADAMW_TORCH,
             torch.optim.AdamW,