Flatpak before 1.16.2 ignores --reinstall for a bundle and fails with
"<id> already installed" when that commit is deployed.
An app install now uninstalls the user's copy and installs again, without
--delete-data, as the launcher does (storytold/craft-launcher#1014). A failure
after that says what happened and what to do.
A self-update never uninstalls the app it runs from: its download goes right
after, so a failed install would leave nothing. That error there means an
earlier update landed and never restarted, so it goes on to the restart.
Root gets a flatpak command, so tests can record the real calls.