Describe the bug

Portal users who are followers of a helpdesk ticket cannot view the ticket if there are other followers (in message_partner_ids) that belong to a different company than the
ticket's company. This causes an AccessError preventing legitimate ticket access or list portal tickets.

To Reproduce

Steps to reproduce the behavior:

1. Setup:
   - Create Company A and Company B
   - Create a helpdesk ticket for Customer A (belonging to Company A)
   - Add Customer A as a follower of the ticket
   - Add User B (belonging to Company B) as a follower of the same ticket
2. Access:
   - Log in as Customer A (portal user)
   - Try to list tickets in portal
   - Try to view the ticket
3. Result:
   - AccessError is raised
   - Customer A cannot list tickets from portal, res.partner rules is raised
   - Customer A cannot view the ticket even though they are the ticket owner and follower

Expected behavior

Portal users who are followers or owners of a ticket should be able to view the ticket and see all followers, regardless of the followers' company affiliation.

Current behavior

When a portal user tries to access a ticket:

1. An AccessError is raised, blocking the entire ticket view or ticket list view