Don't allow the FQDN to match the domain on server installs
    
    Without this the installation is successful but the DNS
    records will not work. With --setup-dns there will be no
    A record for the host (only an NS record) and the PTR record
    will point to the domain name.
    
    Fixes: https://pagure.io/freeipa/issue/9003
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>