ci/papr: Fix artifacts
ci/papr: Fix artifacts

Of course we only notice these things are broken when the CI breaks.

Also add some comments and flip flatpak to `required: true` since it should be
now.

Closes: #1507
Approved by: jlebon

GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree