CORD-2312 unit tests for vsg syncsteps

Change-Id: I745bc90b0c27a28a430282611c79677569ec978d
(cherry picked from commit 3fa6a7ab207a3ef38a659ec37b5cc6f0d312416f)
diff --git a/xos/synchronizer/steps/sync_vsgserviceinstance.py b/xos/synchronizer/steps/sync_vsgserviceinstance.py
index 21cf96e..b062f59 100644
--- a/xos/synchronizer/steps/sync_vsgserviceinstance.py
+++ b/xos/synchronizer/steps/sync_vsgserviceinstance.py
@@ -45,14 +45,7 @@
         super(SyncVSGServiceInstance, self).__init__(*args, **kwargs)
 
     def get_vsg_service(self, o):
-        if not o.owner:
-            return None
-
-        vsg_services = VSGService.objects.filter(id=o.owner.id)
-        if not vsg_services:
-            return None
-
-        return vsg_services[0]
+        return o.owner.leaf_model
 
     def get_extra_attributes(self, o):
         # This is a place to include extra attributes that aren't part of the