Ensure handleUpdateLinkProperties runs on the CS handler thread.

In its own change for ease of rollbacks due to the risk of
possibly crashing existing codepaths.

Bug: 65674744
Test: atest FrameworksNetTests
Test: builds, boots. Wifi, cell data, private DNS work
Change-Id: I2c0acc1c7b8367803f17b4a12c1df0fdfbc29691

services/core/java/com/android/server/ConnectivityService.java

@@ -5558,6 +5558,8 @@ public class ConnectivityService extends IConnectivityManager.Stub
     }
 
     public void handleUpdateLinkProperties(NetworkAgentInfo nai, LinkProperties newLp) {
+        ensureRunningOnConnectivityServiceThread();
+
         if (getNetworkAgentInfoForNetId(nai.network.netId) != nai) {
             // Ignore updates for disconnected networks
             return;