Fix SDPA dispatch & make SDPA CI compatible with torch<2.1.1 (#27940)

fix sdpa dispatch

tests/test_modeling_common.py

@@ -83,6 +83,7 @@ from transformers.utils import (
     is_flax_available,
     is_tf_available,
     is_torch_fx_available,
+    is_torch_sdpa_available,
 )
 from transformers.utils.generic import ModelOutput
 
@@ -778,7 +779,7 @@ class ModelTesterMixin:
         configs_no_init.torchscript = True
         for model_class in self.all_model_classes:
             for attn_implementation in ["eager", "sdpa"]:
-                if attn_implementation == "sdpa" and not model_class._supports_sdpa:
+                if attn_implementation == "sdpa" and (not model_class._supports_sdpa or not is_torch_sdpa_available()):
                     continue
 
                 configs_no_init._attn_implementation = attn_implementation