reduce visual advanced steps

ml-agents/mlagents/trainers/tests/tensorflow/test_simple_rl.py

         PPO_TF_CONFIG,
         hyperparameters=new_hyperparams,
         network_settings=new_networksettings,
-        max_steps=500,
+        max_steps=300,
         summary_freq=100,
         framework=FrameworkType.TENSORFLOW,
     )