[Colors KCM] Only move to next scheme if the selected one is marked for deletion
Summary:
No need to select another scheme if the scheme that is to be removed is not
selected.
Test Plan: Mark a scheme other than the selected one for deletion
Reviewers: Plasma, mart
Reviewed By: Plasma, mart
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D26522