[ECS] [request]: Lifecycle policies for unused task definitions to deregister

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**Tell us about your request**
Lifecycle policies for automatic deregistration for unused ECS task definitions

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

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
I want to inactivate ECS task definitions automatically which are not referenced from ECS services for a certain period.
Immediately after deploying, sometimes we need old task-definition to rollback ECS tasks.
But after a certain period, in most cases, we don't need old task-definition anymore.
So, I want to inactivate the old task-definition after a while.

I would be happy if I could create a non-current version lifecycle setting in ECS task definition like S3.

**Are you currently working around this issue?**
with lambda function

**Additional context**
Nothing

**Attachments**
Nothing