block screen filtering for global menu applet

Summary:
--when the user has enabled PLASMA_USE_QT_SCALING
under X11 environment the screen and window geometries
can not be trusted for comparison. In such case
the global menu should be always visible

BUG: 404500

Test Plan: check that global menu still works properly

Reviewers: Plasma, davidedmundson, broulik

Reviewed By: Plasma, davidedmundson

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D19126