Check convergence and update cached node state

Synchronization could be avoid when one of node
turns to be unavailable. However, it does not necessary
mean node group converge. Additional check and update
is required to update cached state in node selector
and status of factory.

Change-Id: I031e604363abfe1cb3141fa47277084a18ec0416

xenon-common/src/main/java/com/vmware/xenon/services/common/ConsistentHashingNodeSelectorService.java

@@ -637,10 +637,6 @@ private boolean checkAndScheduleSynchronization(long membershipUpdateMicros,
             return false;
         }
 
-        if (!this.isSynchronizationRequired && !this.isSetFactoriesAvailabilityRequired) {
-            return false;
-        }
-
         if (!NodeGroupUtils.isMembershipSettled(getHost(), getHost().getMaintenanceIntervalMicros(),
                 this.cachedGroupState)) {
             checkConvergence(membershipUpdateMicros, maintOp);
@@ -652,11 +648,7 @@ private boolean checkAndScheduleSynchronization(long membershipUpdateMicros,
             return true;
         }
 
-        if (!getHost().isPeerSynchronizationEnabled()) {
-            return false;
-        }
-
-        if (this.isSynchronizationRequired) {
+        if (this.isSynchronizationRequired && getHost().isPeerSynchronizationEnabled()) {
             this.isSynchronizationRequired = false;
             if (isDefaultNodeSelector()) {
                 logInfo("Scheduling synchronization (%d nodes)", this.cachedGroupState.nodes.size());