Fix deleted users follow

[Stef-Rousset]

🎩 What? Why?

When a private user of a non transparent private assembly (or a private participatory process) is deleted, the follows of assembly or its components are also deleted

📌 Related Issues

Link your PR to an issue

• Fixes issue 12851

Testing

1. As an admin, edit an assembly and make it private and non transparent (in the Visibility tab)
2. If there is no meeting, add a meeting component to it
3. Invite "user@example.org" as a private user of this assembly
4. As a user, access to the private assembly and click on the follow button
5. Go to the meeting inside assembly and follow it
6. As an admin, delete the private user "user@example.org"
7. As a user, check that you can’t access to the private assembly anymore
8. As an admin, add again "user@example.org" as a private user
9. As a user, go to the assembly and see that your follow has been deleted
10. As a user, go to the meeting and see that your follow has also been deleted

♥️ Thank you!

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[BarbaraOliveira13]

I ran it locally and it works 🎉