### Description

The new [readiness port](https://www.elastic.co/guide/en/elasticsearch/reference/8.4/advanced-configuration.html#readiness-tcp-port) makes readiness checks on Kubernetes much easier. However the current implementation only allows connections through localhost. TCP probes on Kubernetes are run by the kubelet which is a process running on the Kubernetes node (and not from within the container or the Pod). The [Kubernetes documentation](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#tcp-probes) mentions it, but it is kind of subtle: 

> For a TCP probe, the kubelet makes the probe connection at the node, not in the pod, which means that you can not use a service name in the host parameter since the kubelet is unable to resolve it.


That means a standard Kubernetes readiness probe cannot be used for Elasticsearch:
```
          readinessProbe:
            tcpSocket:
              port: 8080
```

Instead, only an `exec` probe that runs a shell command inside the container can be used that relies in this case on the presence of the `nc` command in the container image:

```
    readinessProbe:
      exec:
        command: ["nc", "-z", "-v", "-w5", "127.0.0.1", "8080"] 
```



server/src/main/java/org/elasticsearch/readiness/ReadinessService.java
try {
                    serverChannel.bind(socketAddress(localhost, portNumber));
                } catch (IOException e) {
                    throw new BindTransportException("Failed to bind to " + NetworkAddress.format(localhost, portNumber), e);
                }
                return null;
            });
            
            if (boundSocket.get() == null) {
                boundSocket.set((InetSocketAddress) serverChannel.getLocalAddress());
                
                BoundTransportAddress boundAddress = boundAddress();
                for (BoundAddressListener listener : boundAddressListeners) {
                    listener.addressBound(boundAddress);
                }
            }
        } catch (Exception e) {
            throw new BindTransportException("Failed to open socket channel " + NetworkAddress.format(localhost, portNumber), e);
        }
        return serverChannel;
    }
    @Override
    protected void doStart() {
        
        this.active = true;
    }
    
    synchronized void startListener() {
        assert enabled(environment);
        if (this.serverChannel != null || this.active == false) {