Symfony version(s) affected: 4.4.0

Description
In Symfony 4.4/5.0 creating multiple WebTestCase clients is deprecated/forbidden. The docs however don't mention anything about it and I don't see any other way of creating multiple clients. What would be the recommended upgrade path?

https://symfony.com/doc/current/testing/insulating_clients.html

This examples throw an exception in SF 5.0

How to reproduce
Just follow the https://symfony.com/doc/current/testing/insulating_clients.html docs

This changes were commited in #32056