update-portal: Clean up details in progress reporting
update-portal: Clean up details in progress reporting

Always report op/n_ops as their last values.
Ensure we never send op >= n_ops
Ensure we always send one and only one 100% running status (== op done)

matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak,matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,matthiasclasen/flatpak,flatpak/flatpak,matthiasclasen/flatpak