[ECR] [request]: Ability to delete images by Cross-Region Replication

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**Tell us about your request**
Proposal would be to add a flag to the ECR Cross Region Replication Settings to enable the replication in both ways - adding **and deleting** images. This would make sure that the replicated repositories are always in sync with the source repository.

**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?**
Currently, Cross Region Replication in ECR only works in one way by distributing images across regions. However, over time this leads to many images in our use case. To keep control over the images in all the regions, we ultimately would like to set the lifecycle policy rules only once in the source repository in ECR to cleanup no longer needed images and want to remove these images in the replicated regions as well. It would be great if it could be possible to also remove images in the replicated regions if they get deleted in the source region repository by using AWS provided functionalities.

**Are you currently working around this issue?**
Our current workaround to solve this problem will be terraform scripting to apply ECR lifecycle policies in all regions to cleanup the images. This is not ideal because we need to keep control and maintain many repositories in the different regions whilst we want to only push and maintain one repository (pushing and cleanup) and would like ECR to handle the replication.

No repository file, test, or entry point is named; begin by reviewing the ECR cross-region replication request and its comment thread. Done means AWS ECR can delete images in replicated regions when they are deleted in the source, using the requested replication setting.

Written by the indexing model from the issue text.