https://pagure.io/centos-infra/issue/1377

Currently we still provide CentOS Linux 7 and Stream 8 through [duffy.ci.centos.org API](https://sigs.centos.org/guide/ci/#duffy-ephemeral-bare-metalvirtual-machines-provider)

We also have our cico workspace container built on top of CentOS Stream 8 and we should migrate it before it's EOL'ed

Plan :

• announce to ci-users list the changes
• rebase [cico-workspace container](https://quay.io/repository/centosci/cico-workspace) on CentOS stream 9 (and test it first)
• remove 8s pools in duffy (and clean-up AWS pre-provisioned instances
• same for 7 (going EOL one month after