`dnsrecord_add` interactive mode might prompt for value of non-existent
arguments `a_part_create_reverse` and `aaaa_part_create_reverse`. This
happens because `dnsrecord_add` extra flags are incorrectly defined as
parts of the respective DNS records.
Remove extra flags from DNS record parts to fix the interactive mode on old
clients talking to new servers. Skip non-existent arguments in the
interactive mode to fix new clients talking to old servers.
https://fedorahosted.org/freeipa/ticket/6457
Reviewed-By: Martin Basti <mbasti@redhat.com>