kubeadm logs tokens before deleting them

Summary: `kubeabdm`'s `delete` command takes as input either a bootstrap token ID, or a full token. Before determining whether the input is just an id or a full token, `kubeadm` logs the input using `klog`. If the deletion fails, the token would remain valid. An attacker who has access to the logs …

// RunDeleteTokens removes a bootstrap tokens from the server.
func RunDeleteTokens(out io.Writer, client clientset.Interface, tokenIDsOrTokens []string) error {
	for _, tokenIDOrToken := range tokenIDsOrTokens {
		// Assume this is a token id and try to parse it
		tokenID := tokenIDOrToken …