Test out all the layers on local CPU.

def mtf_unitransformer_all_layers_tiny():
  """Test out all the layers on local CPU."""
  hparams = mtf_unitransformer_tiny()
  hparams.moe_num_experts = 4
  hparams.moe_expert_x = 4
  hparams.moe_expert_y = 4
  hparams.moe_hidden_size = 512
  hparams.layers = ["self_att", "local_self_att", "moe_1d", "moe_2d", "drd"]
  return hparams