[11.10 EE] Revert Rails.application.env_config after using mock_auth_hash
11-10-stable-ee
was failing for the same reason it was failing in master
last month (https://gitlab.com/gitlab-org/gitlab-ee/issues/11278).
This merge request backports the changes in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/11442/diffs for the 11-10-stable-ee
branch.
Edited by Stan Hu