feat(whitby): switch from nix-serve to harmonia for the cache r/8721

Harmonia is, ostensibly, faster and better and, most importantly, not a giant
pile of wonky Perl.

I've tested locally that Harmonia works with Nix 2.3 (on both ends), so I think
we should be good to go here.

We have a vendored copy of the upstream module for now. We need to fix Nix 2.3
compatibility in upstream for the module, but the service itself works fine.

Change-Id: I3897bb02b83bd466b6fe7077c05728ac49ea4406
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12517
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: sterni <sternenseemann@systemli.org>

0 files changed, 0 insertions, 0 deletions