[FIX] mail: incorrect message order in chatter

Since [1], messages were ordered in ascendant order if the
`after` parameter was passed to the `_message_fetch` method.

This leads to messages being inserted in the wrong order
when several messages are batched then fetched via the
`/thread/messages` route. In practice, this order can
be removed since the `/channel/messages` route already
orders its messages correctly.

1: https://github.com/odoo/odoo/pull/116666/

task-3349175

closes odoo/odoo#123727

X-original-commit: 597b0b00068f6ab99632563faeb2ea18f5c9056f
Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>
Signed-off-by: Stockbauer Matthieu (tsm) <tsm@odoo.com>

addons/mail/models/mail_message.py

@@ -942,7 +942,7 @@ class Message(models.Model):
             domain = expression.AND([domain, [('id', '<', before)]])
         if after:
             domain = expression.AND([domain, [('id', '>', after)]])
-        return self.search(domain, limit=limit, order='id ASC' if after else 'id DESC')
+        return self.search(domain, limit=limit)
 
     def message_format(self, format_reply=True, msg_vals=None):
         """ Get the message values in the format for web client. Since message