[Kickoff] Anchor right of subTitleElement in KickoffItem to arrow.right
Summary: I meant to do this in D19874, but I must have accidentally reset the change.
Test Plan: Looks exactly the same as the screenshots in D19874, which were made with this change
Reviewed By: VDG, filipf, ngraham
Subscribers: filipf, plasma-devel
Differential Revision: https://phabricator.kde.org/D20399