nixos: remove test-config-examples.sh (obsolete)

This file has been non-functional for over two years, since
commit f002a27a80 ("Remove obsolete directory") removed
.../doc/config-examples/.

nixos/tests/test-config-examples.sh

@@ -1,14 +0,0 @@
-#!/bin/sh
-
-# This script try to evaluate all configurations which are stored in
-# doc/config-examples.  This script is useful to ensure that examples are
-# working with the current system.
-
-pwd=$(pwd)
-set -xe
-for i in ../doc/config-examples/*.nix; do
-  NIXOS_CONFIG="$pwd/$i" nix-instantiate \
-      --eval-only --xml --strict > /dev/null 2>&1 \
-      ../default.nix -A system
-done
-set +xe