use correct domain for gcp letsencrypt test
use correct domain for gcp letsencrypt test

Signed-off-by: Panagiotis Xynos <d05cbf8f2ffebe0cf6daa3abd9d896bc6d5e0a30@engineerbetter.com>

EngineerBetter/concourse-up,EngineerBetter/concourse-up,EngineerBetter/concourse-up