remove change to vector_io

Signed-off-by: Francisco Javier Arceo <farceo@redhat.com>

Author: franciscojavierarceo

src/llama_stack/core/routers/vector_io.py

@@ -99,11 +99,6 @@ async def query_chunks(
     ) -> QueryChunksResponse:
         logger.debug(f"VectorIORouter.query_chunks: {vector_store_id}")
         provider = await self.routing_table.get_provider_impl(vector_store_id)
-
-        # Ensure params dict exists
-        if params is None:
-            params = {}
-
         return await provider.query_chunks(vector_store_id, query, params)
 
     # OpenAI Vector Stores API endpoints