Tests: move generate tests to the right mixin and delete redundant tests (#34464)

* tmp commit

* tmp commit

* cull overwrites of deleted tests

* typo

* more specific docstring

* make fixup

* parameterize at the top?

* correction

* more deletions :D

* tmp commit

* for VLMs too

* fix _check_outputs

* test nit

* make fixup

* fix another flaky

* test_generate_from_inputs_embeds -- handle missing attention mask

tests/models/gemma2/test_modeling_gemma2.py

@@ -78,7 +78,6 @@ class Gemma2ModelTest(GemmaModelTest, unittest.TestCase):
     test_pruning = False
     _is_stateful = True
     model_split_percents = [0.5, 0.6]
-    _torch_compile_test_ckpt = "google/gemma-2-9b"
 
     def setUp(self):
         self.model_tester = Gemma2ModelTester(self)