test: improve test-vm-cached-data.js

* verify error message by adding 2nd argument to throws in test-assert

PR-URL: #11974
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

test/parallel/test-vm-cached-data.js

@@ -89,4 +89,4 @@ assert.throws(() => {
   new vm.Script('function abc() {}', {
     cachedData: 'ohai'
   });
-});
+}, /^TypeError: options.cachedData must be a Buffer instance$/);