bug#34033: Offloading sometimes hangs

[Mathieu Othacehe]

Hey,

> Something is going wrong here! I'll keep investigating.

To help us investigate those issues I added a "/status" page, which is
also accessible from a new drop-down menu in the Cuirass navigation bar.

See, https://ci.guix.gnu.org/status.

Hydra has the same interface, but also a "Machine status" page, that
breaks down the running builds machine per machine. I plan to implement
that one next. Reading Hydra code, I also discovered that some part of
the offloading is directly done from Hydra, which talks with the
nix-daemon of the connected build machines, interesting!

While I'm writing, we have 5 running builds for ~1 hour, and 76040 queued
builds. Given the computing power of Berlin, there must be a bottleneck
somewhere.

Thanks,

Mathieu