Align z's to pixel grid in system.svg
Summary: This does the same thing as D20586, but for the Breeze desktop theme. The diff shows a lot of changes because I optimized the SVG.
Test Plan: Looks exactly the same as D20586
Reviewers: VDG, ngraham
Reviewed By: VDG, ngraham
Differential Revision: https://phabricator.kde.org/D20597