Use modern rendering APIs for attribute-behavior fixture (#27883)

The attribute-behavior fixture now uses `createRoot().render()` and
`renderToReadableStream` instead of depdrecated APIs.

This revealed some changes to the snapshots that I annotated for
discussion.

I also added some new tests related to upcoming changes for easier
future diffing.

Also adds support for running the attribute-behavior fixture using Apple
Silicon chips (Apple MBP M-series).