[Fargate] [request]: Support ECS_TASK_METADATA_RPS_LIMIT or similar parameter

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**Tell us about your request**
Support ECS_TASK_METADATA_RPS_LIMIT parameter like the EC2-based ECS agent or a similar configuration in Task Definition.

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

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
Our application running in Fargate is failing to download files from S3 due to API throttling limits on the metadata end point. We would like to increase the limit, particularly /v2/credentials endpoint on the task instance.

**Are you currently working around this issue?**
We are planning to do exponential back-off. However, our pipeline uses a rigorous validation process so it will not be rolled out in time.

**Additional context**
We contacted AWS support and they pointed us to this roadmap. We also discuss about caching the credentials with AWS SDK.

**Attachments**
N/A

No repository files, tests, or implementation entry points are identified in the issue. Start by reviewing the Fargate request and its ECS_TASK_METADATA_RPS_LIMIT comparison; done would mean a supported parameter or similar Task Definition configuration that addresses throttling at the task metadata endpoint.

Written by the indexing model from the issue text.