nixos/tests/common/acme: don't set nameservers for client

The resolver is mainly useful for the ACME server, and acme.nix uses its
own DNS server to test DNS-01 challenges.

nixos/tests/common/acme/client/default.nix

@@ -5,10 +5,6 @@ let
 in
 
 {
-  networking.nameservers = [
-    nodes.acme.config.networking.primaryIPAddress
-  ];
-
   security.acme = {
     server = "https://acme.test/dir";
     email = "hostmaster@example.test";

nixos/tests/common/acme/server/default.nix

@@ -33,9 +33,9 @@
 # override networking.nameservers like this:
 #
 # {
-#   acme = { nodes, ... }: {
+#   acme = { nodes, lib, ... }: {
 #     imports = [ ./common/acme/server ];
-#     networking.nameservers = [
+#     networking.nameservers = lib.mkForce [
 #       nodes.myresolver.config.networking.primaryIPAddress
 #     ];
 #   };