[FIX] stock: discard scrap

- Process a WO (e.g. 'Manual Assembly' from the demo data)
- Create a scrap for component 'Drawer Black'
- A new wizard appears:
  'The product XXX is not available in sufficient quantity'
- Click on 'Discard'

A scrap is created in draft, but it cannot be canceled.

The scrap shouldn't have been created in a first place, but this cannot
be changed in stable. Therefore, we delete it.

opw-1946254

closes odoo/odoo#32122

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

addons/stock/wizard/stock_warn_insufficient_qty.py

@@ -34,3 +34,7 @@ class StockWarnInsufficientQtyScrap(models.TransientModel):
 
     def action_done(self):
         return self.scrap_id.do_scrap()
+
+    def action_cancel(self):
+        # FIXME in master: we should not have created the scrap in a first place
+        return self.scrap_id.sudo().unlink()

addons/stock/wizard/stock_warn_insufficient_qty_views.xml

@@ -44,6 +44,9 @@
             <xpath expr="//field[@name='product_id']" position="after">
                 <field name="scrap_id" invisible="1"/>
             </xpath>
+            <xpath expr="//button[@name='cancel_button']" position="replace">
+                <button string="Discard" name="action_cancel" type="object" class="btn-primary"/>
+            </xpath>
         </field>
     </record>
 </odoo>