[GTK] run-gtk-tests randomly fails while running the xprop comand

[GTK] run-gtk-tests randomly fails while running the xprop comand
https://bugs.webkit.org/show_bug.cgi?id=76817

Reviewed by Philippe Normand.

Temporarily comment the lines related to launching the ATSPI bus
and registry daemon, which are making the bots to fail randomly.

* Scripts/run-gtk-tests:
(TestRunner): Skip TestWebKitAccessibility, as it won't run
properly if the ATSPI infrastructure is not properly initialized.
(TestRunner.run): Comment lines related to initialization of ATSPI.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@105601 268f45cc-cd09-0410-ab3c-d52691b4dbfc