Release 6.22.1: Remove no longer supported calls to final contact interface

[Guest]

The following preliminary calls will be removed from the HTTP API:

- Associate two contacts (Since 6.18.1, Preliminary)
- Dissociate two contacts (Since 6.18.1, Preliminary)
- Get associated contacts of a contact (Since 6.18.1, Preliminary)
- Get association status of two contacts (Since 6.18.1, Preliminary)
- Get contact by uuid (Since 6.18.1, Preliminary)