Steps to reproduce the error:
- Install "contacts" and "whatsapp" module
- Configure WhatsApp Business Account and create a whatsapp template
- Go to Contacts > Create a new contact > add mobile number >
  click on whatsapp button > select template > send message
- reply to message from mobile number
- Delete contact
- Go to Discuss > open channel of contact > send message

Traceback:
```
IndexError: tuple index out of range
  File "odoo/http.py", line 2256, in __call__
    response = request._serve_db()
  File "odoo/http.py", line 1832, in _serve_db
    return self._transactioning(_serve_ir_http, readonly=ro)
  File "odoo/http.py", line 1852, in _transactioning
    return service_model.retrying(func, env=self.env)
  File "odoo/service/model.py", line 134, in retrying
    result = func()
  File "odoo/http.py", line 1830, in _serve_ir_http
    return self._serve_ir_http(rule, args)
  File "odoo/http.py", line 1837, in _serve_ir_http
    response = self.dispatcher.dispatch(rule.endpoint, args)
  File "odoo/http.py", line 2062, in dispatch
    result = self.request.registry['ir.http']._dispatch(endpoint)
  File "odoo/addons/base/models/ir_http.py", line 220, in _dispatch
    result = endpoint(**request.params)
  File "odoo/http.py", line 742, in route_wrapper
    result = endpoint(self, *args, **params_ok)
  File "home/odoo/src/enterprise/saas-17.2/whatsapp/controller/main.py", line 41, in webhookpost
    request.env['whatsapp.message']._process_statuses(value)
  File "home/odoo/src/enterprise/saas-17.2/whatsapp/models/whatsapp_message.py", line 413, in _process_statuses
    whatsapp_message_id._update_message_fetched_seen()
  File "home/odoo/src/enterprise/saas-17.2/whatsapp/models/whatsapp_message.py", line 426, in _update_message_fetched_seen
    channel_member = channel.channel_member_ids.filtered(lambda cm: cm.partner_id == channel.whatsapp_partner_id)[0]
  File "odoo/models.py", line 6580, in __getitem__
    return self.browse((self._ids[key],))
```

https://github.com/odoo/enterprise/blob/a134bea9c6fa1a0806c5501046e358c82d7a3fe5/whatsapp/models/whatsapp_message.py#L428
Here, when user deletes the contact, channel.whatsapp_partner_id will be False,
and channel_member will become an empty tuple,
So when it tries to access the index of an empty tuple,
It will lead to the above traceback.

sentry-5314291061

Forward-Port-Of: odoo/enterprise#62262