[FIX] website_sale: do not display unavailable pricelists

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

addons/website_sale/models/sale_order.py

@@ -268,7 +268,7 @@ class Website(models.Model):
         :param int pl_id: The pricelist id to check
         :returns: Boolean, True if valid / available
         """
-        return pl_id in self.get_pricelist_available(show_visible=False).ids
+        return pl_id in self.get_pricelist_available(show_visible=True).ids
 
     def get_current_pricelist(self):
         """