Update app.go to not call API when host == --pages-domain

What does this MR do?

It was discovered that we make an unnecessary API call to the internal API when the host is pages domain and access control is enabled. This merge request add a check to avoid unnecessary function call.

Changelog: changed

Related to #419

TODO

• I added the Changelog trailer (e.g. Changelog: added) to the commits that need to be included in the changelog
• I added unit tests or they are not required
• I added acceptance tests or they are not required
• I added documentation (or it's not required)
• I followed code review guidelines
• I followed Go Style guidelines