Fixed spotbugs useless issue

Signed-off-by: Kilian Périsset <kilian.perisset@infomaniak.com>

src/main/java/com/owncloud/android/ui/activity/UploadListActivity.java

@@ -198,7 +198,6 @@ public class UploadListActivity extends FileActivity {
     @Override
     protected void onStart() {
         super.onStart();
-        final Optional<User> optionalUser = getUser();
     }
 
     @Override