[IMP] website: merge cache of is_multilang_url with url_rewrite

Fwd-port of 6e87ee09

closes odoo/odoo#64916

X-original-commit: 6e987e6f7f5e6422bb1d04ea8764ab298446ffb0
Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>
Signed-off-by: Olivier Dony (odo) <odo@openerp.com>