FYI: Taskcluster Services Migration

[Dustin Mitchell]

*tl;dr:* Taskcluster, the platform supporting Firefox CI, will be moving to
a new hosting environment during the tree-closing window at the end of
September. This is a major change and upgrade to the platform, but may
cause some bumps along the way.

Taskcluster is in the midst of a few migrations [1], and one of those is
moving to a new hosting environment. This has a few advantages:
* Operations will be managed by professionals (cloudops), not developers
(TC team)
* Administration will be managed by professionals (releng), not developers
(TC team)
* Hosting will be in a more trusted environment (GCP instead of Heroku)
* New, faster UI
* New, faster, more reliable worker-provisioning backend

The downside is that URLs will be changing, likely leaving some dangling
pointers. We've anticipated some of the most common (such as
https://queue.taskcluster.net/ URLs) and are planning workarounds, but
nonetheless anticipate some dead links for a while following the switch.

Dustin

[1]
https://mana.mozilla.org/wiki/pages/viewpage.action?spaceKey=TAS&title=Migrations