remove check_dygraph=False in test_data_norm_op optest (#22335)

* fix bug when grad_op's output not be used in compute kernel in dygraph mode, test=develop

* fix test_data_norm_op.py, test=develop

* polish code style, test=develop

* fix error of data_norm's infershape, test=develop

* polish comment, test=develop

python/paddle/fluid/tests/unittests/test_data_norm_op.py

@@ -217,7 +217,7 @@ class TestDataNormOp(OpTest):
         """
         test check backward, check grad
         """
-        self.check_grad(['X'], 'Y', no_grad_set=set([]), check_dygraph=False)
+        self.check_grad(['X'], 'Y', no_grad_set=set([]))
 
 
 class TestDataNormOpWithSlotDim(OpTest):
@@ -273,7 +273,7 @@ class TestDataNormOpWithSlotDim(OpTest):
         """
         test check backward, check grad
         """
-        self.check_grad(['X'], 'Y', no_grad_set=set([]), check_dygraph=False)
+        self.check_grad(['X'], 'Y', no_grad_set=set([]))
 
 
 class TestDataNormOpWithSyncStats(unittest.TestCase):