Adjust subprocessor test

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

     env_manager = SubprocessEnvManager(
         simple_env_factory, EngineConfig.default_config(), num_envs
     )
-    trainer_config = generate_config(PPO_CONFIG)
+    trainer_config = generate_config(PPO_CONFIG, override_vals={"max_steps": 5000})
     # Run PPO using env_manager
     _check_environment_trains(
         simple_env_factory(0, []),