use aws sdk to validate regions
use aws sdk to validate regions

Signed-off-by: David Wu <48df7c384994ea9863f153fb9de4852705935e92@docker.com>

estesp/distribution,sergeyfd/distribution,sadlil/distribution,docker/distribution,dmcgowan/distribution,yuwaMSFT2/distribution,sadlil/distribution,sergeyfd/distribution,docker/distribution,dmcgowan/distribution,thaJeztah/distribution,thaJeztah/distribution,estesp/distribution,yuwaMSFT2/distribution