[FIX] website_sale: prevent selecting itself as an alternative product

Part of https://github.com/odoo/odoo/pull/37135
task-2070507

addons/website_sale/views/product_views.xml

@@ -98,7 +98,7 @@
                             <field name="website_url" invisible="1"/>
                             <field name="website_id" options="{'no_create': True}" groups="website.group_multi_website"/>
                             <field name="public_categ_ids" widget="many2many_tags" string="Categories"/>
-                            <field name="alternative_product_ids" widget="many2many_tags"/>
+                            <field name="alternative_product_ids" widget="many2many_tags" domain="[('id', '!=', active_id)]"/>
                             <field name="accessory_product_ids" widget="many2many_tags"/>
                             <field name="website_style_ids" widget="many2many_tags" groups="base.group_no_one"/>
                         </group>