Merge pull request #6247 from jtattermusch/benchmark_fail_on_scenario_failure

Actually fail on benchmark scenario failure.

tools/run_tests/run_performance_tests.py

@@ -361,5 +361,6 @@ try:
     sys.exit(1)
 except:
   traceback.print_exc()
+  raise
 finally:
   finish_qps_workers(qpsworker_jobs)