ipaserver/dcerpc: make sure to always return unicode SID of the trust domain
Trusted domain SID could be obtained through different means. When it is
fetched from the AD DC via LDAP, it needs to be extracted from a default
context and explicitly converted to unicode.
https://fedorahosted.org/freeipa/ticket/4246
Reviewed-By: Martin Kosek <mkosek@redhat.com>