recognize groupOfUniqueNames as valid LDAP group object
recognize groupOfUniqueNames as valid LDAP group object

This was already partly done in f88109b but was missed in the
fetchGroups function.

michaelletzgus/nextcloud-server,nextcloud/server,nextcloud/server,andreas-p/nextcloud-server,nextcloud/server,nextcloud/server,andreas-p/nextcloud-server,michaelletzgus/nextcloud-server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,michaelletzgus/nextcloud-server,michaelletzgus/nextcloud-server