nixosTests.buildbot: Test does not evaluate

[tfc]

Describe the bug

On current master (d1dbdf0) the buildbot test does not evaluate:

$ nix-build nixos/tests/buildbot.nix 
trace: warning: In file /home/tfc/src/nixpkgs/nixos/modules/services/continuous-integration/buildbot/master.nix
a list is being assigned to the option config.users.groups.
This will soon be an error as type loaOf is deprecated.
See https://git.io/fj2zm for more information.
Do
  users.groups =
    { unnamed = {...}; ...}
instead of
  users.groups =
    [ { name = "unnamed"; ...} ...]

error: The option `users.groups.unnamed-3.1.buildbot' defined in `/home/tfc/src/nixpkgs/nixos/modules/services/continuous-integration/buildbot/master.nix' does not exist.
(use '--show-trace' to show detailed location information)

Expected behavior

The test should work, before it is ported to python for #72828

cc contributers who touched this test in the past: @Ekleog @lopsided98 @nand0p @fpletz

[worldofpeace]

sounds like #77189

[worldofpeace]

#77324