[Widget Explorer] Continue using a trash can icon for "Uninstallable" category
Summary:
After D20623, some icons change a bit. This patch keeps the delegate using a trash can
icon, and it's more semantically correct as well to use edit-delete over list-remove
Test Plan:
Reviewers: broulik
Reviewed By: broulik
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D20637