[ci skip]

Fix private feature Elasticsearch leak

Closes gitlab-ee#381

See merge request gitlab/gitlabhq!3457

[ci skip]

Add spec to test different combinations.

Add spec

If the request wasn't initiated by gitlab we shouldn't add the new
identity to the user, and instead show that we weren't able to link
the identity to the user.

This should fix: https://gitlab.com/gitlab-org/gitlab-ce/issues/56509