auth.orgUserMap does not work on k8s.sgdev.org

Created by: lguychard

Steps to reproduce:

1. Create an org on k8s.sgdev.org, for instance sourcegraph
2. Through the management console, add the following to critical config:

"auth.userOrgMap": {
    "*": [
      "sourcegraph"
    ]
  }

Expected behavior:

• New & current users are automatically added to the org.

Actual behavior:

• New & current users are not added to the org.

Note: I did not have this issue on a new docker instance running sourcegraph/server:3.5.0-rc.1.