Partial workaround for https://gitlab.gnome.org/GNOME/gnome-menus/7

Upgraders will still have a Sundry app folder in GNOME Shell,
which can be removed by manually running something like
dconf reset -f /org/gnome/desktop/app-folders/

The Sundry app folder is at least better than a X-GNOME-Sundry
app folder.

New installs and everything else that don't use GNOME app folders
won't have a Sundry app folder.