moves to t3 instance
moves to t3 instance

- us-west-2d does not support a t2 medium
instance and we would sometimes select that
zone when deploying our nat

[#164340621]

Signed-off-by: Nick Mahoney <37df72260815dd7c7e09de5254fe02d7d2694eb5@pivotal.io>

pivotal-cf-experimental/bosh-bootloader,pivotal-cf-experimental/bosh-bootloader