HPCC-27359 Move QueryFilesInUse subscription into thread

The WsWorkunits subscribes to Dali about the changes of query
files. The existing subscription runs when the WsWorkunits is
loaded. ESP start process may time out if the subscription
takes a long time.

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

esp/services/ws_workunits/ws_workunitsService.cpp

@@ -479,7 +479,6 @@ void CWsWorkunitsEx::init(IPropertyTree *cfg, const char *process, const char *s
     initContainerRoxieTargets(roxieConnMap);
 #endif
     m_sched.start();
-    filesInUse.subscribe();
 
     //Start thread pool
     xpath.setf("Software/EspProcess[@name=\"%s\"]/EspService[@name=\"%s\"]/ClusterQueryStateThreadPoolSize", process, service);

esp/services/ws_workunits/ws_workunitsService.hpp

@@ -102,6 +102,7 @@ public:
 
     virtual void threadmain()
     {
+        subscribe();
         while (!aborting)
         {
             //prepopulate the cache, lazy mode is very slow