Use different Font Management KCM "All Fonts" icon

Summary:
Needed for D18702.
{F6591513}

Test Plan: Open the Font Management KCM.

Reviewers: #plasma, #vdg, ngraham

Reviewed By: #vdg, ngraham

Subscribers: ngraham, #vdg, plasma-devel, #plasma

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D18785