[ECR] [request]: Please increase ECR repository policy text constraint.

### Community Note

* Please vote on this issue by adding a 👍 [reaction](https://blog.github.com/2016-03-10-add-reactions-to-pull-requests-issues-and-comments/) to the original issue to help the community and maintainers prioritize this request
* Please do not leave "+1" or "me too" comments, they generate extra noise for issue followers and do not help prioritize the request
* If you are interested in working on this issue or have submitted a pull request, please leave a comment

**Tell us about your request**
Currently ECR Repository policy text is limited to 10240 chars (https://docs.aws.amazon.com/AmazonECR/latest/APIReference/API_SetRepositoryPolicy.html#API_SetRepositoryPolicy_RequestSyntax), this is limiting us to add multiple cross account permissions to ECR repository. Can you please increase this limit so that we can add multiple AWS accounts.

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

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
We are settings access policy on per repository level and adding different AWS accounts ids for pulling the images, since we hit with this limit we are blocked to add any new accounts.

**Are you currently working around this issue?**
Not finding any workaround for this.

No repository files, tests, or entry points are identified. Start with the linked ECR SetRepositoryPolicy API documentation and determine whether the 10,240-character limit is service-side; done means the documented policy limit supports the requested cross-account permissions.

Written by the indexing model from the issue text.