Fix plugin deployment

Summary: Remove the special copies for the plugins . This should get master working with plugins on windows and mac os (as well as atelier in the future )

Reviewers: Craft, vonreth

Reviewed By: Craft, vonreth

Subscribers: vonreth, Atelier: AtCore, Craft

Tags: Craft, Atelier: AtCore

Differential Revision: https://phabricator.kde.org/D13407