HPCC-22091 Check ESP service container before running scheduled WU

ESP service container is needed when scheduled ECL WU is running in
WsWorkunits service. When an ESP is started, the WsWorkunits is
loaded before the container is set. the WUSchedule thread inside
the WsWorkunits service should check whether the container is set
before running a scheduled WU.

Signed-off-by: wangkx <kevin.wang@lexisnexis.com>

esp/services/ws_workunits/ws_workunitsHelpers.cpp

@@ -3014,7 +3014,11 @@ int WUSchedule::run()
     unsigned int waitTimeMillies = 1000*60;
     while(!stopping)
     {
-        if (!detached)
+        if (!m_container)
+        {
+            DBGLOG("ECLWorkunit WUSchedule Thread is waiting for container to be set.");
+        }
+        else if (!detached)
         {
             try
             {