Fix CS external dependencies on CarrierDefaultApp

- Use formal API getSystemService to get ConnectivityManager.
- Stop using setProcessDefaultNetworkForHostResolution(), it's
  only used for legacy API startUsingNetworkFeature() but
  CaptivePortalLoginActivity is used requestNetwork(). So remove
  it from CaptivePortalLoginActivity.

Bug: 183068713
Test: atest CarrierDefaultAppUnitTests
Change-Id: Ib3a5dcb70b71ec5b959aeb90a5e3596f3426ceb1

packages/CarrierDefaultApp/src/com/android/carrierdefaultapp/CaptivePortalLoginActivity.java

@@ -86,7 +86,7 @@ public class CaptivePortalLoginActivity extends Activity {
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        mCm = ConnectivityManager.from(this);
+        mCm = getSystemService(ConnectivityManager.class);
         mUrl = getUrlForCaptivePortal();
         if (mUrl == null) {
             done(false);
@@ -161,7 +161,6 @@ public class CaptivePortalLoginActivity extends Activity {
         if (network != null) {
             network = network.getPrivateDnsBypassingCopy();
             mCm.bindProcessToNetwork(network);
-            mCm.setProcessDefaultNetworkForHostResolution(network);
         }
         mNetwork = network;
     }

packages/CarrierDefaultApp/src/com/android/carrierdefaultapp/ProvisionObserver.java

@@ -49,7 +49,7 @@ public class ProvisionObserver extends JobService {
             case PROVISION_OBSERVER_REEVALUATION_JOB_ID:
                 if (isProvisioned(this)) {
                     Log.d(TAG, "device provisioned, force network re-evaluation");
-                    final ConnectivityManager connMgr = ConnectivityManager.from(this);
+                    final ConnectivityManager connMgr = getSystemService(ConnectivityManager.class);
                     Network[] info = connMgr.getAllNetworks();
                     for (Network nw : info) {
                         final NetworkCapabilities nc = connMgr.getNetworkCapabilities(nw);