feat: Run CI integration tests in parallel

I don't know how feasible/easy/difficult this is and whether we have enough compute or not, but this could substantially reduce our CI time. I took a stab at this and ran into some weird issues with rsync

The issue names CI integration tests and rsync but no files or entry points. Start by locating the CI configuration and integration-test jobs, reproduce the rsync issue, and define done as parallel jobs completing reliably with acceptable resource use and passing tests.

Vom Indexierungsmodell aus dem Issue-Text verfasst.