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

**What I did**
Revert sonic-net/sonic-swss#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 #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