* make sure the list of members to add to a group is unique, by
removing duplicates in the inbound list of member IDs
* not attempting to detect duplicate DNs as that should not be
necessary, and results in an error with OpenLDAP; the built-in IDM
does not catch those as of now but the issue is tracked there, and
should not happen due to the UUID filtering in this commit
* remove the corresponding failing test from the list of expected
failures
Fixes 3354
Pascal Bleser
f034f2058f