Fix noindex is missing on static not-found page (#67135)
Render noindex into a flight data and rsc payload when page path is
`/404`
When it's static generation, noindex is not rendered due to the
statusCode from mock request is 200, but we can relying on the pagePath
as `/404` page should always contain `nonidex`
We were missing the noindex before for flight generation, now we'll
render it when it's 404 page.
