adtrust-install: Correctly determine 4.2 FreeIPA servers
    
    We need to detect a list of FreeIPA 4.2 (and above) servers, since
    only there is the required version of SSSD present.
    
    Since the maximum domain level for 4.2 is 0 (and not 1), we can filter
    for any value of ipaMaxDomainLevel / ipaMinDomainLevel attributes
    to generate the list.
    
    https://fedorahosted.org/freeipa/ticket/5199
    
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>