test/sandbox: check tty outcome

This makes no difference currently but has different behaviour in the native sandbox.

Signed-off-by: Ophestra <cat@gensokyo.uk>

test/sandbox/case/preset.nix

@@ -1,6 +1,7 @@
 { fs, ent }:
 {
   name = "preset";
+  tty = false;
 
   want = {
     fs = fs "dead" {
@@ -14,6 +15,7 @@
       } null;
       bin = fs "800001ed" { sh = fs "80001ff" null null; } null;
       dev = fs "800001ed" {
+        console = fs "1a4" null null;
         core = fs "80001ff" null null;
         dri = fs "800001ed" {
           by-path = fs "800001ed" {