[Feature request] Pick default envoy, proxyInit & controller image repository based on the region

[suniltheta]

Is your feature request related to a problem?
Today the Controller (link), Envoy (link) & proxy init (link) images are hardcoded to download docker images from us-west-2 region.

Since all these three images are available globally can we make these default values as default and pick the image from the region where the cluster is deployed?

Especially in China partition we have to manually go and set the image repository where we want to pick the images from, other wise K8s controller will not pull the image deployed in region 'us-west-2' from inside cluster running in China partition.

Image	Parameter	Default today	New Default	Accounts to pick from
AppMesh K8s Controller	image.repository	602401143452.dkr.ecr.us-west-2.amazonaws.com/amazon/appmesh-controller	default	link
AppMesh Envoy sidecar	sidecar.image.repository	840364872350.dkr.ecr.us-west-2.amazonaws.com/aws-appmesh-envoy	default	link
Proxy Route Manager	init.image.repository	840364872350.dkr.ecr.us-west-2.amazonaws.com/aws-appmesh-proxy-route-manager	default	link

Describe the solution you'd like
Based on the region the cluster is deployed we pull the image from that particular region. Otherwise user has to manually set these --set *.image.repository to pick from the region they want.

Describe alternatives you've considered
NA