AWS: Recognize cn-north-1 & us-gov-west-1 regions
AWS: Recognize cn-north-1 & us-gov-west-1 regions

These two regions were accidentally omitted.  This list now matches the
list we use elsewhere (e.g. when choosing an AMI).

Fixes #14420

kubernetes/cloud-provider-aws,kubernetes/cloud-provider-aws,kubernetes/cloud-provider-aws