Remove relref error checking from hugo build

[sean1588]

We currently fail hugo docs builds if it finds a relref that is not able to be resolved. We turned this check off in pulumi-hugo, but this still fails once changes make their way to docs and ends up blocking the deployment pipeline if a relref fails. We have a link checker that runs daily, that notifies us of any failed links, so we are already covered for this by that link checker.