Prefer giving KNotification icons rather than fixed-size pixmaps
Summary:
This lets KNotification pick and appropriate size for however it wants
to display the icon.
Reviewers: mlaurent
Reviewed By: mlaurent
Subscribers: kde-pim
Tags: KDE PIM
Maniphest Tasks: T11637
Differential Revision: https://phabricator.kde.org/D24796