modules: secrets: wireguard: remove unused file

The peer definitions have been inlined into the Wireguard module a long
time ago.

modules/secrets/wireguard/default.nix

@@ -1,30 +0,0 @@
-{ lib, ... }:
-let
-  peerSpec = {
-    # "Server"
-    porthos = {
-      clientNum = 1;
-      externalIp = "91.121.177.163";
-    };
-
-    # "Clients"
-    aramis = {
-      clientNum = 2;
-    };
-
-    richelieu = {
-      clientNum = 3;
-    };
-  };
-
-  makePeer = name: attrs: with lib; {
-    inherit (attrs) clientNum;
-    publicKey = fileContents (./. + "/${name}/public.key");
-    privateKey = fileContents (./. + "/${name}/secret.key");
-  } // optionalAttrs (attrs ? externalIp) {
-    inherit (attrs) externalIp;
-  };
-in
-{
-  peers = builtins.mapAttrs makePeer peerSpec;
-}