[FIX] website_sale: form data lost when applying coupon

Go to eshop with public user
Add items in cart
Checkout, reach shipping and billing address page
Fill the form
Add a coupon

Page will refresh and added content will be lost
This will prevent user from adding a coupon when a form needs to be
filled

opw-2287428

closes odoo/odoo#54101

closes odoo/odoo#54233

Signed-off-by: Nicolas Lempereur (nle) <nle@odoo.com>
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

addons/website_sale/views/templates.xml

@@ -1152,6 +1152,7 @@
                     <div class="row">
                         <div class="col-12 col-xl-auto order-xl-2 d-none d-xl-block">
                             <t t-call="website_sale.cart_summary">
+                                <t t-set="hide_coupon">True</t>
                                 <t t-set="redirect">/shop/address</t>
                             </t>
                         </div>