Use new flatpak_transaction_add_rebase_and_uninstall() API for end-of-life rebases of flatpaks
This landed in flatpak as https://github.com/flatpak/flatpak/issues/3991. gnome-software should be changed to use it if building against a suitably up to date version of flatpak, as it will fix potential atomicity problems with updating end-of-lifed apps.