message: [cluster-test] use jumphost in env var if defined
  Added an option in cluster test runner to use jumphost specified in env
  var if there is one defined.  Fall back to default if not.
  Closes:
  Approved by: andll
diff: @@ -66,7 +66,7 @@ then
  exit 1
  fi
  -JUMPHOST=ssh.${WORKSPACE}.aws.hlw3truzy4ls.com
  +JUMPHOST=${JUMPHOST:-ssh.${WORKSPACE}.aws.hlw3truzy4ls.com}
  ssh $JUMPHOST echo "ssh ok" >/dev/null || (echo "Failed to ssh to jump host $JUMPHOST. Try renew corp canal cert with cc-certs"; exit 1)
  