Revert "[Settings] Support getSystemService(Class<T>)"

This reverts commit d5ccde31a8.

Reason for revert: failure on test cases

Change-Id: I0a179a6ebb5ef1dec566ce6e8facd5f3b82d7c8a

src/com/android/settings/network/NetworkResetRestrictionChecker.java

@@ -31,7 +31,7 @@ public class NetworkResetRestrictionChecker {
 
     public NetworkResetRestrictionChecker(Context context) {
         mContext = context;
-        mUserManager = context.getSystemService(UserManager.class);
+        mUserManager = (UserManager) context.getSystemService(Context.USER_SERVICE);
     }
 
     @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)