Store Docker Images In AWS ECR Public

**What would you like to be added**: Store Images in AWS ECR's public registry https://gallery.ecr.aws/. **Why is this needed**: With Docker Hub now has aggressive rate limiting and one way to get around it is to use another Docker Registry. AWS created public ECR to allow images to be pulled. Would be nice to have grafana stored in multiple registries including ECR, DockerHub and Google's GCR.