Attempting to test automatically the _keys_to_ignore. (#20042)

* Attempting to test automatically the `_keys_to_ignore`.

* Style.

* First fix pass.

* Moving test on its own.

* Another batch.

* Second round removing BatchNorm

* Fixing layoutlmv{2,3} + support older Python.

* Disable miss missing warning.

* Removing dodgy additions.

* Big pass.

* mbart.

* More corrections.

* Fixup.

* Updating test_correct_missing_keys

* Add escape hatch for when the head has no extra params so doesn't need

the missing keys check.

* Fixing test.

* Greener.

* Green ! (except for weird splinter bug).

* Adding a test about `named_parameters` usage.

* Shorten message.

* Apply suggestions from code review

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* After rebase modifications.

* More explicit condition checking.

* Fixing slow tests issues.

* Remove extra pdb.

* Remove print.

* Attempt to make failure consistent + fixing roc_bert.

* Removing the seed  (all tests passing with it).

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

tests/models/auto/test_modeling_auto.py

@@ -119,8 +119,6 @@ class AutoModelTest(unittest.TestCase):
             self.assertIsNotNone(model)
             self.assertIsInstance(model, BertForPreTraining)
             # Only one value should not be initialized and in the missing keys.
-            missing_keys = loading_info.pop("missing_keys")
-            self.assertListEqual(["cls.predictions.decoder.bias"], missing_keys)
             for key, value in loading_info.items():
                 self.assertEqual(len(value), 0)
 

tests/models/bart/test_modeling_bart.py

@@ -424,7 +424,6 @@ class BartModelTest(ModelTesterMixin, GenerationTesterMixin, unittest.TestCase):
     is_encoder_decoder = True
     fx_compatible = True
     test_pruning = False
-    test_missing_keys = False
 
     def setUp(self):
         self.model_tester = BartModelTester(self)
@@ -1445,6 +1444,7 @@ class BartStandaloneDecoderModelTest(ModelTesterMixin, GenerationTesterMixin, un
     fx_comptatible = True
     test_pruning = False
     is_encoder_decoder = False
+    test_missing_keys = False
 
     def setUp(
         self,