Revise update channels

This work adds missing update channels, and moves them to the config file.

It also updates the latest nightly ESR, from 17.0 to 24.0.

A note as per the related issue, I'm unable to test this locally, since I believe a DB is required underneath to draw these contents within the dashboard index page. Perhaps there is a way internally to get around that, or it can be checked in mozmill-sandbox.