Ciao fabrizio,
se non sabglio accedi a quella view dal menu incoming shipment dunque
in stock.view.xml modulo stock search_default_available è settato ad 1 settalo a 0
<record id="action_picking_tree4" model="ir.actions.act_window">
<field name="name">Incoming Shipments</field>
<field name="res_model">stock.picking</field>
<field name="type">ir.actions.act_window</field>
<field name="view_type">form</field>
<field name="view_mode">tree,form,calendar</field>
<field name="domain">[('type','=','in')]</field>
<field name="context">{'contact_display': 'partner_address',"search_default_available":1}</field>
<field name="search_view_id" ref="view_picking_in_search"/>
<field name="help">The Incoming Shipments is the list of all orders you will receive from your suppliers. An incoming shipment contains a list of products to be received according to the original purchase order. You can validate the shipment totally or partially.</field>
</record>
comunque non dovresti modificare i file del modulo ma creane uno custom e sfruttare l'ereditarietà delle view.
Spero di esserti stato d'aiuto