Fix: remove network related flow rules on openstack network removal

Change-Id: I3f6501cfd2474665ed244ff10ae604e7aac2f801
diff --git a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackSwitchingArpHandler.java b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackSwitchingArpHandler.java
index 68fe4df..6eb882e 100644
--- a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackSwitchingArpHandler.java
+++ b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackSwitchingArpHandler.java
@@ -872,7 +872,7 @@
             Network network = event.subject();
 
             if (network == null) {
-                log.warn("Network is not specified.");
+                log.debug("Network is not specified.");
                 return false;
             } else {
                 return network.getProviderSegID() != null;
@@ -897,9 +897,10 @@
                 case OPENSTACK_NETWORK_UPDATED:
                     eventExecutor.execute(() -> processNetworkCreation(event));
                     break;
-                case OPENSTACK_NETWORK_REMOVED:
+                case OPENSTACK_NETWORK_PRE_REMOVED:
                     eventExecutor.execute(() -> processNetworkRemoval(event));
                     break;
+                case OPENSTACK_NETWORK_REMOVED:
                 case OPENSTACK_PORT_CREATED:
                 case OPENSTACK_PORT_UPDATED:
                 case OPENSTACK_PORT_REMOVED: