ipa-dns-install: use LDAPI to connect to DS
ipa-dns-install now uses LDAPI/autobind to connect to DS during the setup of
DNS/DNSSEC-related service and thus makes -p option obsolete.
Futhermore, now it makes more sense to use LDAPI also for API Backend
connections to DS and thus all forms of Kerberos auth were removed.
This fixes https://fedorahosted.org/freeipa/ticket/4933 and brings us closer
to fixing https://fedorahosted.org/freeipa/ticket/2957
Reviewed-By: Martin Basti <mbasti@redhat.com>