gVisor CNI tutorial is not working as expected

### Description

I followed https://gvisor.dev/docs/tutorials/cni/ set up networking for a gVisor sandbox using CNI

For the last step, the server doesn't return anything, which is unexpected, I might misconfigure something, otherwise, the CNI tutorial is broken.

```
$ curl http://${POD_IP}:8000/
curl: (52) Empty reply from server
$ sudo /tmp/runsc/runsc list
ID PID STATUS BUNDLE CREATED OWNER
53b357804046593 1331824 running /tmp/experiment/bundle 2024-08-08T18:17:09.909262116Z root
```

### Steps to reproduce

follow the tutorial at https://gvisor.dev/docs/tutorials/cni/

### runsc version

```shell
gVisor HEAD
```

### docker version (if using docker)

```shell
n/a
```

### uname

_No response_

### kubectl (if using Kubernetes)

_No response_

### repo state (if built from source)

_No response_

### runsc debug logs (if available)

_No response_