[ECS] [request]: Custom log group for containerInsights logs

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**Tell us about your request**
What do you want us to build? I want to have ECS have an option of allowing a custom log group to be used for container insight logs.

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

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
Currently the container insight logs are automatically generated and there is no way of pushing these logs into a custom made log group. This results in not being able to keep track of the logs and the log group retention not being customizable. If we want to keep the logs for extended period of time and monitoring our behavioral changes over time this would be useful.

**Are you currently working around this issue?**
How are you currently solving this problem? Not currently working on this.

**Additional context**
Anything else we should know? No.

**Attachments**
If you think you might have additional information that you'd like to include via an attachment, please do - we'll take a look. (Remember to remove any personally-identifiable information.)

The issue names ECS and Fargate container insights logs but does not identify repository files, tests, or implementation entry points. Start by confirming with maintainers where container insights log-group configuration is represented and what custom-group and retention behavior is expected; done means ECS supports that option for the requested services.

Written by the indexing model from the issue text.