Remove ConnectivityManager and its usages from NetworkStatsService.

NSS needed it for getting VpnInfo[], NetworkState[] and
activeLinkProperties which it used to query via ConnectivityManager.

For VpnInfo[], this was racy as NSS may ignore intermediate changes to a
VPN's underlying networks. See http://b/123961098 for more context.

It may also lead to deadlocks b/w ConnectivityService and
NetworkStatsService. See http://b/126245192 for more info.

This change will ensure that NSS is never contending on any of
ConnectivityService locks.

Bug: 123961098
Bug: 126245192
Bug: 120145746
Test: atest FrameworksNetTests
Change-Id: I57e117bb4e9efe491b19d6b5a479f2d58d1c58e6

services/java/com/android/server/SystemServer.java

@@ -1366,7 +1366,6 @@ public final class SystemServer {
                 ServiceManager.addService(Context.CONNECTIVITY_SERVICE, connectivity,
                         /* allowIsolated= */ false,
                         DUMP_FLAG_PRIORITY_HIGH | DUMP_FLAG_PRIORITY_NORMAL);
-                networkStats.bindConnectivityManager(connectivity);
                 networkPolicy.bindConnectivityManager(connectivity);
             } catch (Throwable e) {
                 reportWtf("starting Connectivity Service", e);