nixos/test-instrumentation: properly import `options` for `qemu`-check

If `qemu-vm.nix` is imported, the option `virtualisation.qemu.consoles`
should be set to make sure that the machine's output isn't rendered on
the graphical window of QEMU.

This is needed when interactively running a NixOS test or in conjunction
with `nixos-build-vms(8)`.

The patch 2578557530 tries to only do this
if the option actually exists, however this condition used to be always
false since `options` wasn't imported in the module and pointed to
`lib.options` due to the `with lib;`-clause.

nixos/modules/testing/test-instrumentation.nix

@@ -1,22 +1,13 @@
 # This module allows the test driver to connect to the virtual machine
 # via a root shell attached to port 514.
 
-{ config, lib, pkgs, ... }:
+{ options, config, lib, pkgs, ... }:
 
 with lib;
 with import ../../lib/qemu-flags.nix { inherit pkgs; };
 
 {
 
-  # This option is a dummy that if used in conjunction with
-  # modules/virtualisation/qemu-vm.nix gets merged with the same option defined
-  # there and only is declared here because some modules use
-  # test-instrumentation.nix but not qemu-vm.nix.
-  #
-  # One particular example are the boot tests where we want instrumentation
-  # within the images but not other stuff like setting up 9p filesystems.
-  options.virtualisation.qemu = { };
-
   config = {
 
     systemd.services.backdoor =