bug 13520: cannot clear vm map during disconnect as xapi still reports them as alive and clearing up the map will have sync report them as Running

reviewed-by: kishan

core/src/com/cloud/hypervisor/xen/resource/CitrixResourceBase.java

@@ -339,9 +339,6 @@ public abstract class CitrixResourceBase implements ServerResource, HypervisorRe
 
     @Override
     public void disconnected() {
-      synchronized (_cluster.intern()) {
-         s_vms.clear(_cluster);
-      }
     }
 
     protected boolean pingdomr(Connection conn, String host, String port) {