test_flake_with_core: no longer auto shutdown vm

We can now execute commands to have a better interface for this.

pkgs/clan-cli/tests/test_flake_with_core/flake.nix

@@ -24,16 +24,6 @@
 
               clan.core.networking.zerotier.controller.enable = true;
               networking.useDHCP = false;
-
-              systemd.services.shutdown-after-boot = {
-                enable = true;
-                wantedBy = [ "multi-user.target" ];
-                after = [ "multi-user.target" ];
-                script = ''
-                  #!/usr/bin/env bash
-                  shutdown -h now
-                '';
-              };
             };
           vm2 =
             { lib, ... }: