[Misc] Consolidate pooler config overrides (#10351)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

tests/engine/test_arg_utils.py

@@ -2,6 +2,7 @@ from argparse import ArgumentTypeError
 
 import pytest
 
+from vllm.config import PoolerConfig
 from vllm.engine.arg_utils import EngineArgs, nullable_kvs
 from vllm.utils import FlexibleArgumentParser
 
@@ -32,9 +33,13 @@ def test_limit_mm_per_prompt_parser(arg, expected):
 
 def test_valid_pooling_config():
     parser = EngineArgs.add_cli_args(FlexibleArgumentParser())
-    args = parser.parse_args(["--pooling-type=MEAN"])
+    args = parser.parse_args([
+        '--override-pooler-config',
+        '{"pooling_type": "MEAN"}',
+    ])
     engine_args = EngineArgs.from_cli_args(args=args)
-    assert engine_args.pooling_type == 'MEAN'
+    assert engine_args.override_pooler_config == PoolerConfig(
+        pooling_type="MEAN", )
 
 
 @pytest.mark.parametrize(