Call verify_go_version at the END of setup_env

Prior to this it would download Go, setup the environment, then (maybe)
download Go again.

I renamed verify_go_version to be internal and fixed all callers.

hack/verify-import-aliases.sh

@@ -26,7 +26,6 @@ KUBE_ROOT=$(dirname "${BASH_SOURCE[0]}")/..
 source "${KUBE_ROOT}/hack/lib/init.sh"
 
 kube::golang::setup_env
-kube::golang::verify_go_version
 
 cd "${KUBE_ROOT}"