New infra playbooks

[ct-martin]

The configuration on the mirror and builder has changed since we originally created the playbooks, and they need updating.

Among the changes needed are:

• We are no longer using Jenkins
• Installation and provisioning of Gitlab CI runner
  • Do we need to install Docker for this?
• Certbot's commands are different from the cron job and need updating (command is not certbot-3 or at least not on this version)
• yum auto-updating
• Devel mirror on the builder

[ct-martin]

Ping @Tjzabel - please let me know if you have anything to add to this