Python: Agent Name Sanitization (#1523)

* a2a agent name sanitization

* fix

* small fix

---------

Co-authored-by: Dmytro Struk <13853051+dmytrostruk@users.noreply.github.com>

python/packages/core/tests/openai/test_openai_responses_client.py

@@ -439,7 +439,7 @@ async def test_get_streaming_response_with_all_parameters() -> None:
             instructions="Stream response test",
             max_tokens=50,
             parallel_tool_calls=False,
-            model="gpt-4",
+            model_id="gpt-4",
             previous_response_id="stream-prev-123",
             reasoning={"mode": "stream"},
             service_tier="default",