uninstall: Use flatpak_dir_list_unused_refs_with_options()
uninstall: Use flatpak_dir_list_unused_refs_with_options()

No need to use the FlatpakInstallation version, because we just
needs the refs as strings, not FlatpakInstalledRef:s

flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak