images: use svgcleaner to reduce logo SVG sizes

images: use svgcleaner to reduce logo SVG sizes

Used svgcleaner[0] with the following safe[1] command:

```
svgcleaner INPUT.svg OUTPUT.svg --indent 1 --resolve-use no \
 --convert-shapes no --group-by-style no --join-arcto-flags no \
 --join-style-attributes no --remove-comments no --remove-declarations no \
 --remove-invisible-elements no --remove-metadata no \
 --remove-nonsvg-attributes no --remove-nonsvg-elements no \
 --remove-text-attributes no --remove-title no \
 --remove-unreferenced-ids no --trim-ids no --ungroup-groups no \
 --list-separator comma
```

Resulting size reductions:

Debian   22.51% smaller
Proxmox  51.00% smaller

Note that the Debian one had a small issue with a unused variable set
which I reported[2] and cleaned up manually for now.

[0]: https://github.com/RazrFalcon/svgcleaner
[1]: https://commons.wikimedia.org/wiki/User:JoKalliauer/Optimization#svgcleaner
[2]: https://github.com/RazrFalcon/svgcleaner/issues/240

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>