Revert: swss: flush g_asicState after each event is done #570 (#1478)

**What I did**
Revert #570
We should only `flush` the orchagent/syncd communication channel when there is no active tasks in orchagent. This will not influence the end-to-end performance in long run but introduce SELECT_TIMEOUT (1 s) latency if there is remaining data left inside the orchagent/syncd communication channel after previous `flush`, which is not a big deal.

Fix sonic-net/sonic-buildimage#5570

orchagent/orchdaemon.cpp

@@ -466,6 +466,12 @@ void OrchDaemon::start()
 
  if (ret == Select::TIMEOUT)
  {
+ /* Let sairedis to flush all SAI function call to ASIC DB.
+ * Normally the redis pipeline will flush when enough request
+ * accumulated. Still it is possible that small amount of
+ * requests live in it. When the daemon has nothing to do, it
+ * is a good chance to flush the pipeline */
+ flush();
  continue;
  }
 
@@ -479,14 +485,6 @@ void OrchDaemon::start()
  for (Orch *o : m_orchList)
  o->doTask();
 
- /* Let sairedis to flush all SAI function call to ASIC DB.
- * Normally the redis pipeline will flush when enough request
- * accumulated. Still it is possible that small amount of
- * requests live in it. When the daemon has finished events/tasks, it
- * is a good chance to flush the pipeline before next select happened.
- */
- flush();
-
  /*
  * Asked to check warm restart readiness.
  * Not doing this under Select::TIMEOUT condition because of