QA workflows don't accept debian:upload artifacts

From: !2445 (comment 697204)

In the QA workflow and its children, we assume that we're dealing with debian:binary-package artifacts in many places. For example any architecture-handling code.

We document the workflows as accepting debian:upload artifacts, but we don't test for supporting these correctly, and in some(many?) cases we don't.

We could probably just resole this by restricting the input to debian:binary-package artifacts (and documenting that).