Mark pipeline tests to skip them easily (#21887)

* Mark pipeline tests to skip them easily

* Mark the mixin as pipeline test

* Update src/transformers/testing_utils.py

Co-authored-by: Yih-Dar <2521628+ydshieh@users.noreply.github.com>

---------

Co-authored-by: Yih-Dar <2521628+ydshieh@users.noreply.github.com>

tests/pipelines/test_pipelines_image_classification.py

@@ -22,6 +22,7 @@ from transformers import (
 )
 from transformers.pipelines import ImageClassificationPipeline, pipeline
 from transformers.testing_utils import (
+    is_pipeline_test,
     nested_simplify,
     require_tf,
     require_torch,
@@ -43,6 +44,7 @@ else:
             pass
 
 
+@is_pipeline_test
 @require_torch_or_tf
 @require_vision
 class ImageClassificationPipelineTests(unittest.TestCase):