[ECR] [Replication]: Support for Cross-Region Deletion of Image Tags replication

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**Tell us about your request**

Expand ECR replication to include syncing removal of tags to the replicated registries.

**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 use tags to manage the lifecycle of images across all regions. Not having the tags removals replicated results in obsolete tags persist in replicated regions, causing unnecessary retention of images. This leads to increased storage costs.

**Are you currently working around this issue?**
N/a

**Additional context**
N/a

**Attachments**
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No repository files, tests, or implementation entry points are identified. Start by reviewing the ECR cross-region replication behavior described here and define the requirements for propagating image-tag removals; done means obsolete tags are removed from replicated registries without affecting image replication.

Written by the indexing model from the issue text.