Removed simulator startup clock test for Qt<5.8.

Summary: Fixes Ubuntu 16.04 test reported as https://launchpadlibrarian.net/469832897/buildlog_ubuntu-xenial-amd64.kstars-bleeding_6%3A3.4.2+202003200441~ubuntu16.04.1_BUILDING.txt.gz

Test Plan: Launchpad build.

Reviewers: mutlaqja

Reviewed By: mutlaqja

Subscribers: kde-edu

Tags: KDE Edu

Differential Revision: https://phabricator.kde.org/D28177