Can't delete a static route in the UI

[Jacopo Rota]

In maas 3.5.0, I can't delete a static route (see video in the attachments).

The websocket request is

{"method":"staticroute.delete","type":0,"params":{"id":2},"request_id":17}

and the response

{"type": 1, "request_id": 17, "rtype": 1, "error": "Object with id (2) does not exist"}

The database contains

```
jacopo=# select * from maasserver_staticroute;
 id | gateway_ip | metric | destination_id | source_id | created | updated
----+------------+--------+----------------+-----------+-------------------------------+-------------------------------
  1 | 10.0.2.1 | 0 | 3 | 2 | 2024-04-04 04:11:34.525107+00 | 2024-04-04 04:11:34.525107+00
(1 row)
```

so it looks like the UI is using the wrong ID