Remove x-out-of-screen-events-buttond test

This test is deprecated as a new one needs to be developed for
wayland images and it is not valid for SDK images.

Reviewed-by: Philip Withnall <philip.withnall@collabora.co.uk>
Signed-off-by: Luis Araujo <luis.araujo@collabora.co.uk>
Differential Revision: https://phabricator.apertis.org/D4946