Disable static page serving for routes covered by middleware

When in static page serving mode (i.e. if `EXPERIMENTAL_MOVE_STATIC_PAGES` is enabled), any middleware is not run for pages that match it, because it's served from the CDN before reaching the origin. Because of this, we should detect if pages are covered by middleware, and if so do not move them, and instead log a warning saying that they won't be served from the CDN.