Merge branch 'ldap_user_attr_method' into 'master'

Move LDAP user attributes to a method

## What does this MR do?

This is a change that supports an EE fix. This small change needs to be made in CE to prevent future merge conflicts. 
See https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/736 for the EE changes.

See merge request !6377