Deduplicate packages build infra

[abhay-krishna]

Currently we have two flows running for the EKS-A curated packages - the old flow that builds and pushes to a single prod packages account and a new regional flow that pushes to the regional packages account. There is a lot of duplication in the build logic of these flows since they use the same scripts, and at the same time, we have two copies of each codepipeline/codebuild job to track and monitor. We need to disable/remove the old flow so that there is only one source of truth for building Curated packages and while doing so, we can include the old packages account in the new flow so that current customers who use that registry continue to keep getting updated artifacts.