[Spike] Outline immediate strategy for OpenShift CI clusters

Long-term strategy is discussed in Outline our CI cluster maintenance/provisioning... (gitlab-org/distribution&25)

Our current fleet includes 4.9 and 4.11 clusters.

4.9 is out of support as of April 18, 2023. Decomissioning 4.9 means we either need to create 4.10 cluster to test against "minimal" upstream-supported version of OCP. 4.10 EOL is set to be Sep 10, 2023. With that in mind we need to decide whether provisioning 4.10 cluster is really worth it at this point.

We also need to provision 4.12 clusters Support OpenShift 4.12 (&57 - closed) keeping in mind that 4.11 support ends in Feb 10, 2024.

So potential solutions:

1. Minimal toil:
   • decomission 4.9
   • provision 4.12
2. Maximum compliance
   • decomission 4.9
   • provision 4.10
   • provision 4.12
   • decomission 4.11

Note

it's worth mentioning that due to extended support lifecycle for "even" releases of OCP we've opted to go with 4.12, 4.14, 4.16, etc. releases to save ourselves additional work of constantly cycling through new OCP clusters.