When pushing a large chain of CLs, builds can fail with OOM issues as
many Nix evaluations of the depot are happening simultaneously.
To work around this, we limit the concurrency of simultaneous Nix
evaluations (i.e. the `:llama` step). This can slow down the start of
builds in a large chain of small changes, but that is a better
tradeoff than failing the builds entirely and making people click
buttons.
Change-Id: If351aaad22d52e2bcf871377f22ab1df594c518d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7501
Reviewed-by: sterni <sternenseemann@systemli.org>
Autosubmit: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
abaa90c3ab