Fix an issue with using non-reusable body types with redirects (#19134)

Closes #19131
Closes #19039

fixes the broken auto-updater.

I had the bright idea of using streams as the most common unit of data
transfer. Unfortunately, streams are not re-usable. So HTTP redirects
that have a stream body (like our remote server and auto update
downloads), don't redirect, as they can't reuse the stream. This PR
fixes the problem and simplifies the AsyncBody implementation now that
we're not using Isahc.

Release Notes:

- N/A