[FIX] website_forum: properly make the description field full width

In the forum form view, the description field is not aligned well and
is too compact. This is because of [1] (and related commits of that big
rework), which changed the way form view groups are rendered (using grid
display).

- eLearning -> Forum -> Forums
- Open any record
- In the "Options" tab, there is a description field at the bottom of
  the view

=> The description field is too compact (hard to view and edit the value
   from the field).

In master, this should in fact be changed to not use any group.

[1]: https://github.com/odoo/odoo/commit/a2b894989ea33364dd29a7d412e4bd4260c1f5ef

closes odoo/odoo#103994

X-original-commit: 3dc42aafffc3c41db732a6e52af7956ea1d0da0e
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/website_forum/views/forum.xml

@@ -91,9 +91,8 @@
                                         </div>
                                     </group>
                                 </group>
-                                <group>
-                                    <field name="description" nolabel="1" placeholder="Description visible on website"/>
-                                </group>
+
+                                <field name="description" placeholder="Description visible on website"/>
                             </page>
                             <page name="karma_gains" string="Karma Gains">
                                 <group name="karma_gain_details">