remove option 'services.nix-bitcoin.enable'

Users can enable the node config just by importing secure-node.nix

modules/nix-bitcoin.nix

@@ -1,3 +1,9 @@
 # This file exists only for backwards compatibility
 
-import ./presets/secure-node.nix
+{ lib, ... }:
+{
+   imports = [
+     ./presets/secure-node.nix
+     (lib.mkRemovedOptionModule [ "services" "nix-bitcoin" "enable" ] "Please directly import ./presets/secure-node.nix")
+   ]
+}

modules/presets/secure-node.nix

@@ -3,7 +3,6 @@
 with lib;
 
 let
-  cfg = config.services.nix-bitcoin;
   operatorCopySSH = pkgs.writeText "operator-copy-ssh.sh" ''
     mkdir -p ${config.users.users.operator.home}/.ssh
     if [ -e "${config.users.users.root.home}/.vbox-nixops-client-key" ]; then