Merge pull request #264870 from K900/test-eval-fix

nixos/tests/predictable-interface-names: fix eval for systemd-stage1

nixos/tests/predictable-interface-names.nix

···
       networking.useDHCP = !withNetworkd;
 
       # Check if predictable interface names are working in stage-1
-      boot.initrd.postDeviceCommands = script;
+      boot.initrd.postDeviceCommands = lib.mkIf (!systemdStage1) script;
 
       boot.initrd.systemd = lib.mkIf systemdStage1 {
         enable = true;