Support Rocky Linux 9 and AlmaLinux 9

Problem/Opportunity Statement

jetstream-cloud/image-build-pipeline!19 introduces RHEL 9-based images to Jetstream2. We should ensure that Exosphere supports these instance operating systems, too.

What would success / a fix look like?

• Verify all expected Exosphere features with Rocky and Alma 9, updating instance configuration (Ansible) code as needed to achieve this
  • with Jetstream2-specific images
  • with upstream images from distro maintainers -- #885 (closed) tracks this.
• Update our documentation, if needed, to reflect that we support Rocky/Alma 9
• Edit configuration to add operating system choices for Rocky and Alma 9 on Jetstrem2