Show the correct delete icons in/out of the trash

Summary: The edit-delete and edit-delete-shred icons were use in the opposite way they should be. edit-delete-shred is for permanent deletion and when there is a trash, edit-delete is used for moving to the trash.

Test Plan:
Old

New

Reviewers: VDG, KDE PIM: KMail, mlaurent, ngraham

Reviewed By: VDG, mlaurent, ngraham

Subscribers: kde-pim

Tags: KDE PIM

Differential Revision: https://phabricator.kde.org/D24377