MALTDS-95: Enable DNS reverse resolution in IPAdev defaults

Because of some limitations of the 389ds LDAP server used by FreeIPA, it is not possible for it to support multiple Kerberos identities. Hence it cannot accept tickets featuring its canonical FQDN (as enabled rDNS resolution clients do, i.e. CC7) AND the ones featuring the service's alias (disabled rDNS, i.e. C8 clients).

As a consequence, we re-enable rDNS resolution for now, in order to fix authentication against IPA's LDAP, as it is a mandatory service to retrieve keytabs and users/groups information.