MXS-619: Temporarily disable the fix

The fix isn't fully functional as closed DCBs never process the events
they receive. The mechanism would work if certain events would be
processed but they'll have to be fixed in a later release.

server/core/routingworker.cc

@@ -559,8 +559,6 @@ void RoutingWorker::register_zombie(DCB* pDcb)
 
 void RoutingWorker::delete_zombies()
 {
-    Zombies not_ready;
-
     // An algorithm cannot be used, as the final closing of a DCB may cause
     // other DCBs to be registered in the zombie queue.
 
@@ -569,17 +567,8 @@ void RoutingWorker::delete_zombies()
         DCB* pDcb = m_zombies.back();
         m_zombies.pop_back();
 
-        if (can_close_dcb(pDcb))
-        {
-            dcb_final_close(pDcb);
-        }
-        else
-        {
-            not_ready.push_back(pDcb);
-        }
+        dcb_final_close(pDcb);
     }
-
-    m_zombies.insert(m_zombies.end(), not_ready.begin(), not_ready.end());
 }
 
 bool RoutingWorker::pre_run()