Improve tests

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

     optimizer = create_test_poca_optimizer(
         dummy_config, use_rnn=rnn, use_discrete=discrete, use_visual=visual
     )
-    time_horizon = 15
+    time_horizon = 30
     trajectory = make_fake_trajectory(
         length=time_horizon,
         observation_specs=optimizer.policy.behavior_spec.observation_specs,

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

 
     trainer_settings = attr.evolve(dummy_config)
     trainer_settings.network_settings.memory = (
-        NetworkSettings.MemorySettings(sequence_length=8, memory_size=10)
+        NetworkSettings.MemorySettings(sequence_length=16, memory_size=10)
         if use_rnn
         else None
     )
     )
     # Time horizon is longer than sequence length, make sure to test
     # process trajectory on multiple sequences in trajectory + some padding
-    time_horizon = 15
+    time_horizon = 30
     trajectory = make_fake_trajectory(
         length=time_horizon,
         observation_specs=optimizer.policy.behavior_spec.observation_specs,
 
     for key, val in run_out.items():
         assert type(key) is str
-        assert len(val) == 15
+        assert len(val) == time_horizon
-        assert len(all_memories) == 15
+        assert len(all_memories) == time_horizon
 
     run_out, final_value_out, _ = optimizer.get_trajectory_value_estimates(
         trajectory.to_agentbuffer(), trajectory.next_obs, done=True