Remove last breeze-dark icons
Rational:
In Plasma we use Breeze and re-color. Same on Windows and macOS and soon on other DEs. That means the better dark variants are never used beside the user sets Breeze Dark in Plasma or some other DE. Therefore the ones in the 'normal' theme must be ok for re-coloring, if not that needs fixing, as most of our users will see them.
If they are gone, I can streamline the dark theme generation, too, that would be a nice side effect, as that is then just 're-color' the normal one without exceptions.
The remaining dark icons are:
- icons-dark/actions/12/object-fill.svg
- icons-dark/actions/16/object-fill.svg
- icons-dark/actions/16/paint-gradient-linear.svg
- icons-dark/actions/22/antivignetting.svg