i want to change some options of the field user_id in a purchase order but the following xml/xpath does not seem to work:

        <record model="ir.ui.view" id="purchase_order_extended_form">
            <field name="name">purchase.purchase_order_extended_form</field>
            <field name="model">purchase.order</field>
            <field name="inherit_id" ref="purchase.purchase_order_form" />
            <field name="arch" type="xml">
           
                <xpath expr="//field[@name='user_id']" position="attributes">
                        <attribute name="options">{'no_open': True,'no_create': True,'no_quick_create':True,'no_create_edit':True}</attribute>
                </xpath>
            </field>
        </record>

please give any hints whats wrong. i just want to remove the "Open" Icon next to the many2one field.

this