[V0 Deprecation] Deprecate --disable-frontend-multiprocessing (#37612)

Signed-off-by: sfeng33 <4florafeng@gmail.com>

tests/entrypoints/openai/completion/test_completion_with_prompt_embeds.py

@@ -83,11 +83,8 @@ def example_prompt_embeds(hf_runner):
     return [_encode_embeds(item) for item in example_embeddings]
 
 
-@pytest.fixture(scope="module", params=["", "--disable-frontend-multiprocessing"])
-def server_with_prompt_embeds(default_server_args, request):
-    if request.param:
-        default_server_args.append(request.param)
-
+@pytest.fixture(scope="module")
+def server_with_prompt_embeds(default_server_args):
     with RemoteOpenAIServer(MODEL_NAME, default_server_args) as remote_server:
         yield remote_server