Improve app list padding under the header
Summary: Make sure the delegates don't touch the header. Looks cleaner this way.
Test Plan:
Featured page, before:
Featured page, after:
App list page, before:
App list page, after:
Reviewers: Discover Software Store, apol
Reviewed By: Discover Software Store, apol
Subscribers: plasma-devel, abetts
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D10548