Some unit tests were failing after ipa-adtrust-install has been run on the
IPA server, due to missing attributes ('ipantsecurityidentifier') and
objectclasses ('ipantuserattrs' and 'ipantgroupattrs'). This patch detects if
ipa-adtrust-install has been run, and adds missing attributes and objectclasses
where appropriate.
https://fedorahosted.org/freeipa/ticket/3852