[FIX] point_of_sale: display POS related info in contact form again

In 6b55539dc7 the "container_row_stock"
group in stock.view_partner_stock_form was hidden using
groups="base.group_no_one". The issue is that the POS used a group
inside of this group that it modified to display the associated
barcode of the partner and the loyalty points of the partner. So
although the code still worked, the actual information was invisible.

To fix it we inherit the view directly from where it is created, namely
base.view_partner_form which is a bit nicer than inheriting from an
already inherited view.

addons/point_of_sale/res_partner_view.xml

@@ -5,9 +5,9 @@
         <record id="view_partner_property_form" model="ir.ui.view">
             <field name="name">res.partner.pos.form.inherit</field>
             <field name="model">res.partner</field>
-            <field name="inherit_id" ref="stock.view_partner_stock_form"/>
+            <field name="inherit_id" ref="base.view_partner_form"/>
             <field name="arch" type="xml">
-                <xpath expr="//group[@name='warehouse']" position="before">
+                <xpath expr="//page[@name='sales_purchases']/group">
                     <group string="Point of Sale" name="point_of_sale">
                         <field name="barcode" />
                     </group>