util: don't depend on the nautilus GSettings schema

util: don't depend on the nautilus GSettings schema

Without the desktop, even Nautilus hardcodes "Home" in all places
nowadays (except for the desktop itself). I think a run-time dependency
on nautilus being installed (GSettings will abort if the schema is not
found) is not worth it to keep compatibility with the desktop.

(Also, nautilus itself could probably hardcode "Home" for the desktop as
well and remove the preference).

https://bugzilla.gnome.org/show_bug.cgi?id=659895