Do not pop VLAN for traffic that goes to the pair port

Note: popVlan is effective to L2 interface group that gets created while creating L2 multicast group. 
The popVlan has nothing to do with L2 multicast group itself.

Change-Id: I63baf88bfd626b19dcfdf654e4e184e48886f7fc
diff --git a/app/src/main/java/org/onosproject/segmentrouting/xconnect/impl/XconnectManager.java b/app/src/main/java/org/onosproject/segmentrouting/xconnect/impl/XconnectManager.java
index ec8a6bd..d4a7430 100644
--- a/app/src/main/java/org/onosproject/segmentrouting/xconnect/impl/XconnectManager.java
+++ b/app/src/main/java/org/onosproject/segmentrouting/xconnect/impl/XconnectManager.java
@@ -1011,7 +1011,7 @@
             vlanMulticastNextId = flowObjectiveService.allocateNextId();
             addMulticastGroupNextObjectiveId(key, vlanMulticastNextId);
             vlanMulticastNextObjBuilder.addTreatment(
-                    DefaultTrafficTreatment.builder().popVlan().setOutput(pairPort).build()
+                    DefaultTrafficTreatment.builder().setOutput(pairPort).build()
             );
         }
         vlanMulticastNextObjBuilder.withId(vlanMulticastNextId);