[FIX] website_partner: correct demo data root->admin

The root user is now the sudoable superuser. The demo data should be
over admin user and not root user.

opw-1907486
closes #28534

addons/website_partner/data/website_partner_demo.xml

 <?xml version="1.0" encoding="utf-8"?>
 <odoo>
 
-    <record id="base.partner_root" model="res.partner">
+    <record id="base.partner_admin" model="res.partner">
         <field name="website_published">True</field>
     </record>
     <record id="base.partner_demo" model="res.partner">