[FIX] base: residue after making res_name a non-stored field

res_name is made non-stored in 8fffe89b0481af057fd6908a52af775578b9fce1
but the groupby filter using the field is not. The filter has to be
removed as well because groupby only works with stored fields.

closes odoo/odoo#39396

X-original-commit: 495124497c733b4bb272fb0d65e132b024a99917
Signed-off-by: pimodoo <pimodoo@users.noreply.github.com>

odoo/addons/base/views/ir_attachment_views.xml

@@ -78,7 +78,6 @@
                         <filter string="Type" name="type" domain="[]" context="{'group_by':'type'}" groups="base.group_no_one"/>
                         <filter string="Company" name="company" domain="[]" context="{'group_by':'company_id'}" groups="base.group_multi_company"/>
                         <filter string="Creation Date" name="creation_month" domain="[]" context="{'group_by':'create_date'}"/>
-                        <filter string="Attached Document Name" name="attached_document_name" domain="[]" context="{'group_by': 'res_name'}"/>
                     </group>
                 </search>
             </field>