Reset staging-next-version environment

It's been months since it's been cleaned up. So some data have accumulated there.

It'd nice to clean it up.

It's the occasion to also ensure db1 (dbs) and storage1 (objstorage) don't run extra kube services (adding missing affinities to chart they need to, e.g. kafka...).

[1] https://docs.softwareheritage.org/sysadm/deployment/howto-reset-next-version-environment.html