Draft: CI: add "needs" dependencies to all test-stage jobs

Experimental, and maybe controversial?

Immediate motivation is that currently rust-recent in the "build" phase is quite slow, and unnecessarily blocks the pipeline from making progress since most jobs don't actually need its artifacts.

It looks like in the past, similarly small/empty "needs" lists were removed to intentionally block. I think maybe so that other jobs would be prioritized? But that has some adverse effects on overall pipeline latency, as above ^.