[autotests] Extend test tables of SlidingPopupsTest

Summary:
Check that the Sliding Popups effect grabs windows no matter in what
order it and the Scale effect are loaded.

Test Plan: Ran the test.

Reviewers: KWin, davidedmundson

Reviewed By: KWin, davidedmundson

Subscribers: kwin

Tags: KWin

Differential Revision: https://phabricator.kde.org/D15729