Pass default value to the zendesk field

The form doesn't remember the selected option after a form error. The default value should be passed down to the zendesk field.
>  $element[$field_name]['#value'] = $element['#value'];

Is this going to force `$element['#value']` in the submission? Do we need it to be:

```php
$element[$field_name]['#default_value'] = $element['#value'];
```