Cleanup tests to deduplicate static response construction (#1023)

* Cleanup tests to deduplicate static response construction

* Fix docstring formatting

Author: tconley1428

temporalio/contrib/openai_agents/_temporal_openai_agents.py

@@ -77,11 +77,7 @@ def set_open_ai_agent_temporal_overrides(
 
     Returns:
         A context manager that yields the configured TemporalTraceProvider.
-
     """
-    if model_params is None:
-        model_params = ModelActivityParameters()
-
     previous_runner = get_default_agent_runner()
     previous_trace_provider = get_trace_provider()
     provider = TemporalTraceProvider(