Updated the project's pages component requirements during domain verification.

What does this MR do and why?

To prevent users running into 500 errors during domain verification, we've added the need for a project to have its Pages component enabled prior to setting up domain verification.

As a result of an RFH here: https://gitlab.com/gitlab-com/sec-sub-department/section-sec-request-for-help/-/issues/395

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