Less dynamic pages manifest path (#90581)
_Two steps forward, one step back_
Reverts https://github.com/vercel/next.js/pull/88641 and https://github.com/vercel/next.js/pull/88806
I ended up having to keep the build id in `_next/data` routes anyway (and made the id a constant if skew protection is enabled). This was because it was utterly impossible to change the routes from `_next/data/:buildId/*` to `_next/data/*` in the builder in a backwards-compatible way.
So there is no need to remove the build id from `_next/static` here either. It just makes testing a huge pain because the paths keep changing
