Error if reading Request Store inside Prerender (#70775)
Stacked on #70768.
We should never access Request Store inside Prerender since those stores
should be mutually exclusive.
This forces us to explicitly handle Draft Mode in Prerender/Cache which
previously was just implicitly isEnabled false. This no longer errors
getting draftMode() in "use cache" since it's a way to just override all
caches.
One remaining thing to fix is after() should be allowed in prerender and
cache.
