Cover the full-upgrade scenario in CI (Bookworm -> Sid)
User may hit a case where after a full-upgrade, the MariaDB Server is not working anymore (removed, not started, etc.). See: #1004262. This CI steps makes sure that after a full-upgrade, the MariaDB Server is still working and running.
This is done by doing a full-upgrade from Bookworm to Sid (installing MariaDB packages from artifacts in the full-upgrade process).
Note that doing the full upgrade from Stable (Bullseye as of today) to Sid is not possible in docker, see #1008202 and the discussion in !18 (closed).
Edited by Faustin Lammler