Template:Domain client realmd prep

1. Ensure the realmd package is installed on the test client (e.g. su -c 'dnf install realmd')
2. Remove the sssd, freeipa-client and samba-client packages (e.g. su -c 'dnf remove sssd samba-client') from the test client, they should be installed by realmd if necessary
3. Unless you wish to test pending updates, disable the 'updates-testing' repository so realmd does not install packages from it: su -c 'dnf config-manager --set-disabled updates-testing'