[IMP] stock: hide product category in on-hand quantity view

The product category is not relevant here and needs to be hidden by
default (Can still be selected on the right).

Task-2428819

Part-of: odoo/odoo#74364

addons/stock/views/stock_quant_views.xml

@@ -129,7 +129,7 @@
                 <field name="product_id" attrs="{'readonly': [('id', '!=', False)]}"
                        readonly="context.get('single_product', False)" force_save="1"
                        options="{'no_create': True}"/>
-                <field name="product_categ_id" optional="show"/>
+                <field name="product_categ_id" optional="hide"/>
                 <field name="location_id" attrs="{'readonly': [('id', '!=', False)]}"
                        invisible="context.get('hide_location', False)"
                        options="{'no_create': True}"/>