Revert "nixos/nix-daemon.nix: assert distributedBuilds and buildMachi…

…nes!=[]"

This reverts commit 67b6e56.
This reverts commit 250885d.

Causes issues for some configs, see 67b6e56

nixos/modules/services/misc/nix-daemon.nix

@@ -500,13 +500,6 @@ in
 
   config = {
 
-    assertions = [
-      {
-        assertion = config.nix.distributedBuilds || config.nix.buildMachines == [];
-        message = "You must set `nix.distributedBuilds = true` to use nix.buildMachines";
-      }
-    ];
-
     nix.binaryCachePublicKeys = [ "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=" ];
     nix.binaryCaches = [ "https://cache.nixos.org/" ];