Add e2e test for public IPs

Add an e2e test for public service IPs.
Here use an array and `ip` should be declared local as well.

```shell
  local ip ips_array=() public_ips
  for ip in ${4:-}; do
    ips_array+=("${ip}")
  done
  public_ips=$(join ", " "${ips_array[@]}")
```