For discussion: Tidy infrastructure team repos

There's a lot of repos here that we no longer use as a team. Some are clearly deprecated, i.e. have been moved to the attic.

The ones I'm not sure of:

- boxes
- boxgrinder-appliances
- machine-bootstrap

Some of these may still be active and maintained, but I'd question if we should install them _by default_ for the GOV.UK Infrastructure Team if they're not directly related to GOV.UK.