private static String servers(ZookeeperServerConfig config) {
        return Configurator.getServerConfig(config.server().stream().filter(server -> ! server.retired()).toList(), -1)
                           .entrySet().stream().map(entry -> entry.getKey() + "=" + entry.getValue()).collect(joining(","));
    }
Starts zookeeper server and supports reconfiguring zookeeper cluster. Keep this as a component
without injected config, to make sure that it is not recreated when config changes.

@author hmusum
zookeeper-server/zookeeper-server-common/src/main/java/com/yahoo/vespa/zookeeper/Reconfigurer.java