enforce test_parallel_executor_transformer and test_image_classification_resnet to run in serial (#12545)

Author: jacquesqiao

python/paddle/fluid/tests/unittests/CMakeLists.txt

@@ -50,6 +50,8 @@ list(REMOVE_ITEM TEST_OPS test_parallel_executor_crf)
 list(REMOVE_ITEM TEST_OPS test_parallel_executor_fetch_feed)
 list(REMOVE_ITEM TEST_OPS test_dist_se_resnext)
 list(REMOVE_ITEM TEST_OPS test_dist_transformer)
+list(REMOVE_ITEM TEST_OPS test_parallel_executor_transformer)
+list(REMOVE_ITEM TEST_OPS test_image_classification_resnet)
 foreach(TEST_OP ${TEST_OPS})
     py_test_modules(${TEST_OP} MODULES ${TEST_OP})
 endforeach(TEST_OP)
@@ -64,3 +66,5 @@ py_test_modules(test_parallel_executor_crf MODULES test_parallel_executor_crf SE
 py_test_modules(test_parallel_executor_fetch_feed MODULES test_parallel_executor_fetch_feed SERIAL)
 py_test_modules(test_dist_transformer MODULES test_dist_transformer SERIAL)
 py_test_modules(test_dist_se_resnext MODULES test_dist_se_resnext SERIAL)
+py_test_modules(test_parallel_executor_transformer MODULES test_parallel_executor_transformer SERIAL)
+py_test_modules(test_image_classification_resnet MODULES test_image_classification_resnet SERIAL)