Add test to make sure that unwanted local nets disconnect correctly

Also add some toString() methods that were useful in debugging.

Test: new test in CSLocalAgentTests
Change-Id: Ife95815e39d92bbef84b1c5ea75a151882590d09
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index d8417c1..da01f49 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -9006,6 +9006,9 @@
             return;
         }
 
+        if (VDBG) {
+            Log.v(TAG, "Update local network config " + nai.network.netId + " : " + newConfig);
+        }
         final LocalNetworkConfig.Builder configBuilder = new LocalNetworkConfig.Builder();
         // TODO : apply the diff for multicast routing.
         configBuilder.setUpstreamMulticastRoutingConfig(