[FIX] sale_timesheet: hide by default allow_non_billable in timesheet

Before this commit, the non_allow_billable field is always display in
the 'All Timesheets' tree view. This field is used when a timesheet is
non billable and the user wants to render this timesheet as billable
timesheet, he can uncheck this field.

This commit hides this field by default in this view.

closes #67055

Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>

addons/sale_timesheet/views/hr_timesheet_views.xml

@@ -42,7 +42,7 @@
         <field name="inherit_id" ref="hr_timesheet.timesheet_view_tree_user"/>
         <field name="arch" type="xml">
             <xpath expr="//field[@name='user_id']" position="after">
-                <field name="non_allow_billable" attrs="{'invisible': [('non_allow_billable', '=', False)]}"/>
+                <field name="non_allow_billable" attrs="{'invisible': [('non_allow_billable', '=', False)]}" optional="hide"/>
             </xpath>
         </field>
     </record>