Migration tool: strip out runtime k8s annotations

[nicoloboschi]

Fixes: https://github.com/datastax/kaap/issues/119

• Only keep and show annotations that are not related to k8s, kubectl or helm

private static boolean keepAnnotation(Map.Entry<String, ?> e) {
        final String key = e.getKey();
        if (key.equals("checksum/config")) {
            return false;
        }
        if (key.startsWith("kubectl.")) {
            return false;
        }
        if (key.startsWith("meta.helm.sh/")) {
            return false;
        }
        if (key.startsWith("deployment.kubernetes.io")) {
            return false;
        }
        return true;
    }