DNS install check: Fix overlapping DNS zone from the master itself
    
    The change to allow overlapping zone to be from the master itself has
    introduced two issues: The check for the master itself should only executed
    if options.force and options.allow_zone_overlap are both false and the
    reverse zone check later on was still handling ValueError instead of
    dnsutil.DNSZoneAlreadyExists.
    
    Both issues have been fixed and the deployment with existing name servers
    is properly working again.
    
    Fixes: https://pagure.io/freeipa/issue/8150
    Signed-off-by: Thomas Woerner <twoerner@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>