The KDE and GNOME 'apps' tests for Firefox both invented their
own 'oh look Firefox is running' needle, even though we already
had one. The GNOME one was broken by the removal of the app
title bar in Firefox 66.
Instead of having three needles for the same thing, let's just
throw the 'apps' ones out and use the pre-existing one from
needles/firefox for all cases.
Signed-off-by: Adam Williamson <awilliam@redhat.com>
