CI: Simplify path to relocatable amd64+i386 build of pressure-vessel

Avoid the word "production", which could easily be mistaken for an official release. It's here for historical reasons. We used to do two separate relocatable installations, one with production-like compiler options, and one unoptimized and unstripped for debugging; but I removed the latter in commit 8649f766 "CI: Skip unpackaged scout builds" in mid 2021, because it slowed down CI and was rarely useful.

/cc @denittis