[FIX] sale_margin: confusing margin percentage in pivot

Steps to reproduce the bug:
- Activate Margins in Sales > Settings
- Go to the pivot view of quotations
- In Measures, click Margin (%)

Bug:
Margin percentages are aggregated by computing the sum of the margin sub-percentages instead of using the data of the aggregated row (i.e. agg. margin / agg. total).

Explanation:
This is one of the flaws of the pivot view. The best way to solve this would be to create a custom aggregation in PostgreSQL.
This commit is just hiding the measure for now.

opw:2349896

closes odoo/odoo#60354

X-original-commit: 1e3fc6894b13d51a3f6327653afbf8d5a316a21d
Signed-off-by: backspac <backspac@users.noreply.github.com>

addons/sale_margin/views/sale_margin_view.xml

@@ -44,4 +44,15 @@
         </field>
     </record>
 
+    <record model="ir.ui.view" id="sale_margin_sale_order_pivot">
+        <field name="name">sale.order.margin.view.pivot</field>
+        <field name="model">sale.order</field>
+        <field name="inherit_id" ref="sale.view_sale_order_pivot"/>
+        <field name="arch" type="xml">
+            <pivot position="inside">
+                <field name="margin_percent" invisible="1"/>
+            </pivot>
+        </field>
+    </record>
+
 </odoo>