[libkwineffects] Delete EffectsHandler::deleteRootProperty
Summary:
The method is not used by any Effect and is X11 specific, thus better
remove it for good.
Reviewers: KWin, Plasma on Wayland
Subscribers: plasma-devel, kwin
Tags: Plasma on Wayland, KWin
Differential Revision: https://phabricator.kde.org/D3298