I’d expect it would be similar to under NS7: wait until the update is available through the Software Center (which in the case of NS8 means, wait until the Docker container is updated).
This will empty the file with the code that checks for a new version and presents an update channel. So this info is no longer show, however it will still show the installed version. Exactly what I needed in 1 command, since, indeed, the config parameters do not function properly.