desktop: Remove obsolete Bugzilla entries
The X-GNOME-Bugzilla-*
entries were for use by bug-buddy, a GNOME 2
technology that's been gone for over a decade. These entries are
obsolete and can be removed from the desktop file.
The desktop file then has no variables so does not need to be
configured. It is renamed from *.in.in
to *.in
to reflect that and
build files are updated for this change.