[ONOS-6266] 'garbageCollect' is not working for groups after ONOS restart

Change-Id: I1e2a5c78d64f8f5cec6352011f3fc6362c9937e5
diff --git a/core/store/dist/src/main/java/org/onosproject/store/group/impl/DistributedGroupStore.java b/core/store/dist/src/main/java/org/onosproject/store/group/impl/DistributedGroupStore.java
index b8d4e03..df8a99c 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/group/impl/DistributedGroupStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/group/impl/DistributedGroupStore.java
@@ -167,8 +167,9 @@
     private boolean allowExtraneousGroups = ALLOW_EXTRANEOUS_GROUPS;
 
     @Activate
-    public void activate() {
+    public void activate(ComponentContext context) {
         cfgService.registerProperties(getClass());
+        modified(context);
         KryoNamespace.Builder kryoBuilder = new KryoNamespace.Builder()
                 .register(KryoNamespaces.API)
                 .nextId(KryoNamespaces.BEGIN_USER_CUSTOM_ID)