trusts: use ipaNTTrustPartner attribute to detect trust entries
Trust entries were found by presence of ipaNTSecurityIdentifier
attribute. Unfortunately this attribute might not be there due the bug.
As replacement for this, attribute ipaNTTrustPartner can be used.
Note: other non trust entries located in cn=trusts subtree can be
Reviewed-By: Alexander Bokovoy <email@example.com>
Reviewed-By: Tomas Babej <firstname.lastname@example.org>