Update loglevel icons

Summary:
Some of these icons don't even exist in breeze, others are semantically wrong. This causes problems when porting away from using pixmaps.

I'm not 100% happy with the selection, but better than nothing I guess

Reviewers: #plasma, davidedmundson

Reviewed By: #plasma, davidedmundson

Differential Revision: https://phabricator.kde.org/D26347