[master] Move Oracle image repository to lhcb-dirac group

Moves the oracle DB container to the lhcb-dirac group instead of it being a personal repository. Unfortunately it's not possible to both:

• keep the existing image under cburr (or have a redirect)
• keep the deployment token the same

I've decided to keep the deployment token the same rather than require everyone to update the secrets in their forks.

I'll rebase !833 (merged) on top of this so it doesn't conflict when this is propagated to devel.