Add RH Puppet VM testing

This is possible thanks to:

• Install centos-gpg-keys in RHEL8: https://gitlab.cern.ch/ai-config-team/ai-tools/-/merge_requests/457
• Add yum-plugin-protectbase package install before we remove all bootstrap repos: https://gitlab.cern.ch/ai-config-team/ai-tools/-/merge_requests/458
• LOS-774: epel-release should be installed after RHEL bootstrapping repos: https://gitlab.cern.ch/ai-config-team/ai-tools/-/merge_requests/456
  • Already in production
• RH images do not have /etc/BUILDTIME: https://gitlab.cern.ch/ai-config-team/cern_puppet_centos_functional_tests/-/merge_requests/2
• Search for cloud-init logs in /var/log/messages if RHEL7 : https://gitlab.cern.ch/ai-config-team/cern_puppet_centos_functional_tests/-/merge_requests/3