Fix broken user removal

Check target user instead of current user, when deciding if
user can be stopped.

Bug: 26207032
Change-Id: Ibf9cb827943f8fbf8fa3b96a9e04c96d11a36d0a

services/core/java/com/android/server/am/UserController.java

@@ -1222,7 +1222,7 @@ final class UserController {
     }
 
     private boolean isCurrentUserLocked(int userId) {
-        return mCurrentUserId == userId || mTargetUserId == userId;
+        return userId == getCurrentOrTargetUserIdLocked();
     }
 
     int setTargetUserIdLocked(int targetUserId) {