Enable more test_torchscript (#16679)

* update _create_and_check_torchscript

* Enable test_torchscript

* clear_class_registry

Co-authored-by: ydshieh <ydshieh@users.noreply.github.com>

tests/van/test_modeling_van.py

@@ -124,7 +124,6 @@ class VanModelTest(ModelTesterMixin, unittest.TestCase):
     all_model_classes = (VanModel, VanForImageClassification) if is_torch_available() else ()
 
     test_pruning = False
-    test_torchscript = False
     test_resize_embeddings = False
     test_head_masking = False
     has_attentions = False