Docs: update the query destination table legacy file to use query_and_wait API

samples/client_query_destination_table_legacy.py

@@ -36,8 +36,8 @@ def client_query_destination_table_legacy(table_id: str) -> None:
     """
 
     # Start the query, passing in the extra configuration.
-    query_job = client.query(sql, job_config=job_config)  # Make an API request.
-    query_job.result()  # Wait for the job to complete.
+    results = client.query_and_wait(sql, job_config=job_config)  # Make an API request.
+    results.result()  # Wait for the job to complete.
 
     print("Query results loaded to the table {}".format(table_id))
     # [END bigquery_query_legacy_large_results]