set skipTaskbar on SurfaceEvent::SurfaceCreated
Summary: makes sure the flag is set on time
Test Plan: can't get the panelcontroller in the taskbar anymore
Reviewers: Plasma, hein, broulik
Reviewed By: Plasma, hein, broulik
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D18186