Move HelpDeskCreds note to first column in admin

The note is the main thing we need to find the creds, given that many use the same email address, so move that column to the start in the admin list view.

v1.0.0

Initial release suitable for running services on Zendesk only, or Zendesk-Halo.

N.B. issue TS2-345 means this release is unsuitable for production use with Halo-only operation: https://uktrade.atlassian.net/browse/TS2-345