[kcmkwin/kwineffects] Use new Kirigami ListSectionHeader component

Summary:
This allows all the section headers to always have the same look and feel and be
adjusted in just one place.

Depends on D23049

Test Plan: {F7181776}

Reviewers: #vdg, kwin, GB_2, #kwin

Reviewed By: #vdg, GB_2

Tags: #kwin

Maniphest Tasks: T10384

Differential Revision: https://phabricator.kde.org/D23055