!2094 修复percentile线程在停止时候休眠10s导致数据库空载下也停止耗时长的问题

Merge pull request !2094 from zhangxubo/master_bugfix

src/gausskernel/cbb/instruments/percentile/percentile.cpp

@@ -220,6 +220,7 @@ NON_EXEC_STATIC void PercentileMain()
         pgstat_report_activity(STATE_IDLE, NULL);
         t_thrd.percentile_cxt.need_reset_timer = true;
         g_instance.stat_cxt.force_process = false;
+        if (t_thrd.percentile_cxt.need_exit) break;
         sleep(SLEEP_INTERVAL);
     }
     elog(LOG, "instrumention percentile ended");