[Core] Add batch parallel VAE decode (#8162)

Signed-off-by: QianCyrus <101633534+QianCyrus@users.noreply.github.com>

tests/diffusion/model_loader/test_diffusers_loader.py

@@ -721,7 +721,7 @@ def test_initialize_model_sets_current_diffusion_config_during_model_constructio
 
     od_config = SimpleNamespace(
         model_class_name="DummyPipeline",
-        parallel_config=SimpleNamespace(vae_patch_parallel_size=1, sequence_parallel_size=1),
+        parallel_config=DiffusionParallelConfig(vae_patch_parallel_size=1, sequence_parallel_size=1),
         vae_use_slicing=False,
         vae_use_tiling=False,
     )