No conv bn folding in ipex to avoid warning (#19870)

* no conv bn folding in ipex

* no flag in training

* comment
Co-authored-by: Sander Land <sander@chatdesk.com>

src/transformers/trainer.py

@@ -1280,7 +1280,8 @@ class Trainer:
 
         if not training:
             model.eval()
-            model = ipex.optimize(model, dtype=dtype, level="O1")
+            # conv_bn_folding is disabled as it fails in symbolic tracing, resulting in ipex warnings
+            model = ipex.optimize(model, dtype=dtype, level="O1", conv_bn_folding=False)
         else:
             if not model.training:
                 model.train()