Return lockService from createComponents (#670)

Signed-off-by: Craig Perkins <[email protected]>

src/main/java/org/opensearch/jobscheduler/JobSchedulerPlugin.java

@@ -127,7 +127,7 @@ public Collection<Object> createComponents(
         clusterService.addListener(this.sweeper);
         clusterService.addLifecycleListener(this.sweeper);
 
-        return Collections.emptyList();
+        return List.of(this.lockService);
     }
 
     @Override