openai: Removed tool_calls from completion chunk after other chunks have already been sent. (#29649)

- **Description:** Before sending a completion chunk at the end of an
OpenAI stream, removing the tool_calls as those have already been sent
as chunks.
- **Issue:** -
- **Dependencies:** -
- **Twitter handle:** -

@ccurme as mentioned in another PR

---------

Co-authored-by: Chester Curme <chester.curme@gmail.com>

libs/partners/openai/langchain_openai/chat_models/base.py

@@ -1483,6 +1483,9 @@ class BaseChatOpenAI(BaseChatModel):
         chat_message = chat_result.generations[0].message
         if isinstance(chat_message, AIMessage):
             usage_metadata = chat_message.usage_metadata
+            # Skip tool_calls, already sent as chunks
+            if "tool_calls" in chat_message.additional_kwargs:
+                chat_message.additional_kwargs.pop("tool_calls")
         else:
             usage_metadata = None
         message = AIMessageChunk(