[FIX] stock_picking_wave: remove picking from a wave

When removing a picking from a wave,
it should simply remove the link between
the picking and the wave, not remove the picking itself.

opw-677590

addons/stock_picking_wave/stock_picking_wave_view.xml

@@ -23,7 +23,7 @@
                             <field name="user_id"/>
                         </group>
                         <separator string="Pickings"/>
-                        <field name="picking_ids" widget="many2many" domain="[('state', 'not in', ('done', 'cancel'))]">
+                        <field name="picking_ids" widget="many2many" domain="[('state', 'not in', ('done', 'cancel'))]" options="{'not_delete': True}">
                             <tree>
                                 <field name="name"/>
                                 <field name="backorder_id"/>