Avoid importing all models when instantiating a pipeline (#24960)

* Avoid importing all models when instantiating a pipeline

* Remove sums that don't work

src/transformers/pipelines/zero_shot_image_classification.py

@@ -18,10 +18,10 @@ if is_vision_available():
     from ..image_utils import load_image
 
 if is_torch_available():
-    from ..models.auto.modeling_auto import MODEL_FOR_ZERO_SHOT_IMAGE_CLASSIFICATION_MAPPING
+    from ..models.auto.modeling_auto import MODEL_FOR_ZERO_SHOT_IMAGE_CLASSIFICATION_MAPPING_NAMES
 
 if is_tf_available():
-    from ..models.auto.modeling_tf_auto import TF_MODEL_FOR_ZERO_SHOT_IMAGE_CLASSIFICATION_MAPPING
+    from ..models.auto.modeling_tf_auto import TF_MODEL_FOR_ZERO_SHOT_IMAGE_CLASSIFICATION_MAPPING_NAMES
     from ..tf_utils import stable_softmax
 
 logger = logging.get_logger(__name__)
@@ -66,9 +66,9 @@ class ZeroShotImageClassificationPipeline(Pipeline):
 
         requires_backends(self, "vision")
         self.check_model_type(
-            TF_MODEL_FOR_ZERO_SHOT_IMAGE_CLASSIFICATION_MAPPING
+            TF_MODEL_FOR_ZERO_SHOT_IMAGE_CLASSIFICATION_MAPPING_NAMES
             if self.framework == "tf"
-            else MODEL_FOR_ZERO_SHOT_IMAGE_CLASSIFICATION_MAPPING
+            else MODEL_FOR_ZERO_SHOT_IMAGE_CLASSIFICATION_MAPPING_NAMES
         )
 
     def __call__(self, images: Union[str, List[str], "Image", List["Image"]], **kwargs):

src/transformers/pipelines/zero_shot_object_detection.py

@@ -14,7 +14,7 @@ if is_torch_available():
 
     from transformers.modeling_outputs import BaseModelOutput
 
-    from ..models.auto.modeling_auto import MODEL_FOR_ZERO_SHOT_OBJECT_DETECTION_MAPPING
+    from ..models.auto.modeling_auto import MODEL_FOR_ZERO_SHOT_OBJECT_DETECTION_MAPPING_NAMES
 
 logger = logging.get_logger(__name__)
 
@@ -60,7 +60,7 @@ class ZeroShotObjectDetectionPipeline(ChunkPipeline):
             raise ValueError(f"The {self.__class__} is only available in PyTorch.")
 
         requires_backends(self, "vision")
-        self.check_model_type(MODEL_FOR_ZERO_SHOT_OBJECT_DETECTION_MAPPING)
+        self.check_model_type(MODEL_FOR_ZERO_SHOT_OBJECT_DETECTION_MAPPING_NAMES)
 
     def __call__(
         self,