*Second in series after https://invent.kde.org/plasma/plasma-workspace-wallpapers/-/merge_requests/17*
Another patch will follow from the translations SVN, after I figure out how to work with it.
In kwin repo alone, there's another 4MB in savings with funny files like those:
```
kwin/po/ru/docs/kcontrol/windowspecific/tbird-reminder-info.png
[oxipng] Reduced by 768.94 KB (-96.42%) from 797.52 KB
```
Summary: We don't need them in the toplevel directory.
Test Plan: Compiles.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D18771
