It should not be possible via /shop/change_pricelist/<pl_id>
to change to a pricelist that is not marked as selectable.

is_pricelist_available method should do that, but is not,
because it calls get_pricelist_available with show_visible=True,
instead of show_visible=False

:param bool show_visible: if True, we don't display pricelist where
selectable is False (Eg: Code promo)

Closes #17220