Note:
 * The `autocompleteContactReference` and `autocompleteContactSearch` settings don't seem to be really stored as such.
 * The form includes various hacks which effectively saves these fields in `contact_reference_options` and `contact_autocomplete_options`.
 * At runtime, the application logic checks for `contact_reference_options` and `contact_autocomplete_options`.
 * This situation predates the declarations of `autocompleteContactReference` and `autocompleteContactSearch` in `Search.setting.php`. It seems likely
   that these settings have never been useful.

The fields still have some hacks, but they should be a bit easier to read/trace/grep.