Change "following fields were present in the request but ignored" log from warn to debug (#36173)

Signed-off-by: Tyler Michael Smith <tlrmchlsmth@gmail.com>

vllm/entrypoints/openai/engine/protocol.py

@@ -49,7 +49,7 @@ class OpenAIBaseModel(BaseModel):
 
         # Compare against both field names and aliases
         if any(k not in field_names for k in data):
-            logger.warning(
+            logger.debug(
                 "The following fields were present in the request but ignored: %s",
                 data.keys() - field_names,
             )