Fix race condition of invalidation (#47586)
Currently, we always invalidate the compiler during `ensurePage` but that might cause an issue when the compilation is slow (and other cases too):
<img width="836" alt="CleanShot-2023-03-28-B4dOAWJU@2x" src="https://user-images.githubusercontent.com/3676859/228087347-0b0eff94-d920-47b3-97b3-894272672e74.png">
So this PR modifies the `ensurePage` promise after invalidation to always wait for that additional rebuilds, if that's also caused by this invalidation.
fix NEXT-893 ([link](https://linear.app/vercel/issue/NEXT-893))
