FIX Setting `$only_available_in` to `private` visibility
FIX Setting `$only_available_in` to `private` visibility

Config engine throws deprecation warnings when this is accessed through the Config engine
helpfulrobot/zucchi-widgets,hailwood/silverstripe-widgets,silverstripe/silverstripe-widgets,silverstripe/silverstripe-widgets,helpfulrobot/zucchi-widgets,silverstripe/silverstripe-widgets,helpfulrobot/zucchi-widgets,hailwood/silverstripe-widgets,hailwood/silverstripe-widgets