Fix krunner's alt+f2 on wayland

Summary:
Don't go through the workaround introduced for X11 that makes it go mental.

BUG: 385693

Test Plan: Have been a happy krunner user since

Reviewers: Plasma, davidedmundson

Reviewed By: Plasma, davidedmundson

Subscribers: ngraham, davidedmundson, plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D10197