Fixes: https://github.com/nodejs/node/issues/42164
If the given port number isn't associated with any service name,
the `service` resolved from `dns.lookupService` can be a numeric
string representing the port number.
PR-URL: https://github.com/nodejs/node/pull/42596
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Akhil Marsonya <akhil.marsonya27@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
