Fix XDGV6 popup test

Summary:
We had a data funciton...then didn't use it, effectively skpping half of
the point of the test.

Test Plan: Ran the test

Reviewers: #kwin, mart

Reviewed By: #kwin, mart

Subscribers: romangg, kde-frameworks-devel

Tags: #frameworks

Differential Revision: https://phabricator.kde.org/D13495