gocd-agent / gocd-server: Reduce test memory requirements so Hydra builds

nixos/tests/gocd-agent.nix

···
     gocd_agent =
       { config, pkgs, ... }:
       {
-        virtualisation.memorySize = 2048;
+        virtualisation.memorySize = 2046;
         services.gocd-agent = {
           enable = true;
         };

nixos/tests/gocd-server.nix

···
 #   1. GoCD server starts
 #   2. GoCD server responds
 
-import ./make-test.nix ({ pkgs, ...} : 
+import ./make-test.nix ({ pkgs, ...} :
 
 {
   name = "gocd-server";
···
 nodes = {
   gocd_server =
     { config, pkgs, ... }:
-    { 
-      virtualisation.memorySize = 2048;
+    {
+      virtualisation.memorySize = 2046;
       services.gocd-server.enable = true;
     };
 };