fix(testing): Reset log adapter in mock session

The mock session was not preserving the @log_adapter.class_logger
decorator from the Session class, causing issues in the mock
environment.

This change resets the API methods tracking after session creation
in the mock, ensuring that the decorator system works correctly.

Author: shuoweil

bigframes/testing/mocks.py

@@ -160,6 +160,12 @@ def query_and_wait_mock(query, *args, job_config=None, **kwargs):
     )
     session._queries = queries  # type: ignore
     session._job_configs = job_configs  # type: ignore
+
+    # Reset the log adapter to clear any session creation tracking
+    import bigframes.core.log_adapter as log_adapter
+
+    log_adapter.get_and_reset_api_methods()
+
     return session