[CI failed]Revert "[Config Refactor] Derive deploy override fields from stage config" (#3287)

Signed-off-by: Gao Han <hgaoaf@connect.ust.hk>

tests/entrypoints/test_async_omni_diffusion_config.py

@@ -4,7 +4,6 @@
 import pytest
 from vllm.utils.argparse_utils import FlexibleArgumentParser
 
-from vllm_omni.config.stage_config import deploy_override_field_names
 from vllm_omni.engine.async_omni_engine import AsyncOmniEngine
 from vllm_omni.entrypoints.cli.serve import OmniServeCommand, _create_default_diffusion_stage_cfg
 
@@ -31,15 +30,6 @@ def test_default_stage_config_includes_cache_backend():
     assert engine_args["model_stage"] == "diffusion"
 
 
-def test_default_stage_config_ignores_none_deploy_overrides():
-    """Ensure nullified deploy override defaults do not alter diffusion defaults."""
-    baseline = AsyncOmniEngine._create_default_diffusion_stage_cfg({})[0]
-    nullified_overrides = {name: None for name in deploy_override_field_names()}
-    stage_cfg = AsyncOmniEngine._create_default_diffusion_stage_cfg(nullified_overrides)[0]
-
-    assert stage_cfg == baseline
-
-
 def test_default_cache_config_used_when_missing():
     """Ensure default cache_config is synthesized when only backend is given."""
     stage_cfg = AsyncOmniEngine._create_default_diffusion_stage_cfg(