[Fargate] [request]: Support for terminating a Task only after all containers have stopped

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**Tell us about your request**

To support game servers hosted in multiple containers within a single Task, it would be useful to support Task termination only after all the containers have stopped (instead of the essential containers functionality). This would allow running stateful sessions on multiple containers of the same type and recycle the Task once all the containers have stopped.

**Which service(s) is this request for?**

Fargate / ECS

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**

Currently to synchronize the termination of multiple stateful containers, you need to make sure all of them marked essential (one or all for example), wait for the termination of the other containers. The idea would be to have a Fargate Task host 10 game sessions on 10 game server containers and terminate once all of them are done (to rotate for new fresh Tasks).

**Are you currently working around this issue?**

Yes, I have all of the containers marked as "essential" and will wait in the processes until all other containers are done (by checking the status with a Lambda function)

Start by reviewing the Fargate/ECS task lifecycle and the current essential-container termination behavior described in the request. Compare it with the stated Lambda workaround and define how a task should terminate only after every container has stopped. Done means the requested all-container termination behavior is supported without requiring every container to be marked essential.

Written by the indexing model from the issue text.