don't ship legacy SysV initscripts + dhcpd[6].service improvements
    
    dhcpd6: move '-cf /etc/dhcp/dhcpd6.conf' from sysconfig/dhcpd6 to dhcpd6.service
    run 'chown -R dhcpd:dhcpd /var/lib/dhcpd/' before starting dhcpd/dhcpd6 service
           for the case where leases file is owned by root:root as a
           consequence of running dhcpd without '-user dhcpd -group dhcpd' (#744292)