Put in place automatic container registry cleanup

CI generates a plenty of container images (1 per commit) and they piled up since CI was put in place to reach today 12060 images...

And these consume a lot of S3 space provided by our group.

I have put in place some automatic rules to clean the registry automatically everyday.

First clean up round is scheduled for 11/11/2021 around 11:40.

I will close the ticket once it has proven to be a transparent process.