fix tf ghost tests

ml-agents/mlagents/trainers/tests/test_ghost.py

     trainer_params = dummy_config
     trainer = PPOTrainer("test", 0, trainer_params, True, False, 0, "0")
     trainer.seed = 1
-    policy = trainer.create_policy("test", mock_specs)
-    policy.create_tf_graph()
+    policy = trainer.create_policy("test", mock_specs, create_graph=True)
-    to_load_policy = trainer.create_policy("test", mock_specs)
-    to_load_policy.create_tf_graph()
-    to_load_policy.init_load_weights()
+    to_load_policy = trainer.create_policy("test", mock_specs, create_graph=True)
 
     weights = policy.get_weights()
     load_weights = to_load_policy.get_weights()

ml-agents/mlagents/trainers/tests/torch/test_ghost.py

     trainer_params = dummy_config
     trainer = PPOTrainer("test", 0, trainer_params, True, False, 0, "0")
     trainer.seed = 1
-    policy = trainer.create_policy("test", mock_specs, create_graph=True)
+    policy = trainer.create_policy("test", mock_specs)
-    to_load_policy = trainer.create_policy("test", mock_specs, create_graph=True)
+    to_load_policy = trainer.create_policy("test", mock_specs)
 
     weights = policy.get_weights()
     load_weights = to_load_policy.get_weights()