refactor: automatic options for overlays, fix build

nixosModules/pxvirt-guest.nix

@@ -1,24 +1,12 @@
 {
-  modulesPath,
   lib,
   config,
   ...
 }:
 {
-  # Import unconditionally — the module only defines options, activating nothing by default.
-  imports = [ (modulesPath + "/virtualisation/proxmox-lxc.nix") ];
-
   options.my.pxvirtGuest.enable = lib.mkEnableOption "Proxmox LXC guest configuration";
 
   config = lib.mkIf config.my.pxvirtGuest.enable {
-    # TODO is this needed?
-    # nix.settings.sandbox = false;
-
-    proxmoxLXC = {
-      manageNetwork = false;
-      privileged = false;
-    };
-
     # Let Proxmox host handle fstrim
     services.fstrim.enable = false;