[Settings] Convert to getSystemService(Class<T>)

Change to getSystemService(Class<T>) to align the capability with framework
part.

Bug: 179640862
Test: local
Change-Id: I1b4812044fc4876bec6645570049a60f9470dbbd

src/com/android/settings/wifi/WifiNoInternetDialog.java

@@ -102,7 +102,7 @@ public final class WifiNoInternetDialog extends AlertActivity implements
             }
         };
 
-        mCM = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
+        mCM = getSystemService(ConnectivityManager.class);
         mCM.registerNetworkCallback(request, mNetworkCallback);
 
         final NetworkInfo ni = mCM.getNetworkInfo(mNetwork);