Change the const for the unreachable network

Changing the const used for the unreachable network for per-app
functionality for those apps whose traffic for the default network we
wish to lose connectivity as dictated by per app network preferences.
This is being done as per changes in https://r.android.com/1643182.

Bug: 181579204
Test: atest FrameworksNetTests
Change-Id: I1bffadfa03a6221096100c9e0457ea00f94027a3
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index 7ea3738..e3ce7a3 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -6296,8 +6296,8 @@
     // Request used to optionally keep vehicle internal network always active
     private final NetworkRequest mDefaultVehicleRequest;
 
-    // TODO replace with INetd.DUMMY_NET_ID when available.
-    private static final int NO_SERVICE_NET_ID = 51;
+    // TODO replace with INetd.UNREACHABLE_NET_ID when available.
+    private static final int NO_SERVICE_NET_ID = 52;
     // Sentinel NAI used to direct apps with default networks that should have no connectivity to a
     // network with no service. This NAI should never be matched against, nor should any public API
     // ever return the associated network. For this reason, this NAI is not in the list of available