BootstrapUser defines bootstrap user name
const BootstrapUser = "token-bootstrap-client"
func RetrieveValidatedConfigInfo(cfg *kubeadmapi.Discovery, timeout time.Duration) (*clientcmdapi.Config, error)
RetrieveValidatedConfigInfo connects to the API Server and tries to fetch the cluster-info ConfigMap It then makes sure it can trust the API Server by looking at the JWS-signed tokens and (if CACertHashes is not empty) validating the cluster CA against a set of pinned public keys