Update airgapped netcat flag deprecation
Fixes failure: https://gitlab.com/gitlab-org/gitlab/-/issues/334269
Docker shell command: `docker exec gitlab-ee-38d56568 bash -c "nc -zv -w 10 35.227.35.254 80 && (echo \"Regular connectivity netcat check passed.\" && exit 0) || (echo \"Regular connectivity netcat check failed.\" && exit 1)"`
Regular connectivity netcat check failed.
nc: invalid option -- 'z'
netcat has deprecated the -z
flag an alternative is to use nmap: nmap sT <IP> -p <port>