Revert "cjdns test: exercise host builder logic"

This reverts commit daf3ba426b.

This is an alternative to 0ba3d429a7,
which disables the test outright.  Briefly, exercising builders which
rely on import-from-derivation can cause Hydra jobsets to time out.

nixos/tests/cjdns.nix

@@ -57,7 +57,6 @@ import ./make-test.nix ({ pkgs, ...} : {
                   connectTo."192.168.0.1:1024}" =
                     { password = carolPassword;
                       publicKey = carolPubKey;
-                      hostname = "carol";
                     };
                 };
             };