nixos: Fix systemd-boot test

[roberth]

Description of changes

Apparently the nodes don't share the host store anymore?

cc @RaitoBezarius is this necessary or is it a bug in the test framework? I don't see where the test disables forwarding of the host store.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 23.11 Release Notes (or backporting 23.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

[roberth]

@ofborg test systemd-boot.switch-test

[RaitoBezarius]

cc @RaitoBezarius is this necessary or is it a bug in the test framework? I don't see where the test disables forwarding of the host store.

With bootloaders (i.e. "full system images"), you get your own /nix/store, I was exploring getting "noNixStore" in those situations for tests that does not require it: #227883

It is a fallout of mountHostNixStore = !useBootLoader; default.

It's more like a target for further refactor/fixes.

[RaitoBezarius]

Precise analysis here: #227881 (comment)