Long setting with stochastic discrete model, changed ppo steps.

def rlmb_long_stochastic_discrete_25steps():
  """Long setting with stochastic discrete model, changed ppo steps."""
  hparams = rlmb_long_stochastic_discrete()
  hparams.ppo_epoch_length = 25
  hparams.simulated_rollout_length = 25
  hparams.simulated_batch_size = 32
  return hparams