UPSTREAMJOB_BUILD_NUMBER parameter is not honored when starting a test_Tails_ISO_* job manually

If I click Build with Parameters on a test job, and type a custom UPSTREAMJOB_BUILD_NUMBER, the test suite job will disregard this info and instead use the default: Git commit and artifacts of the last successful build job. Indeed, I can't find any code or config that would make Jenkins use the specified upstream job build.

Meta: I don't think we should spend much, if any, time to fix this. I'm creating this issue mostly to document it, so that developers who experience it don't waste too much time.

To Do

• Remove from tails/puppet-code (https://gitlab.tails.boum.org/tails/puppet-code/-/merge_requests/45)
• Remove from tails/jenkins-jobs
• Remove from wiki/src/contribute/release_process/test/automated_tests.mdwn in tails/tails (https://gitlab.tails.boum.org/tails/tails/-/merge_requests/2402)
• Check that jobs still work fine
  • build
  • automatically started reproducibly_build
    • https://jenkins.tails.boum.org/job/reproducibly_build_Tails_ISO_stable/4723/console
  • manually started reproducibly_build
    • https://jenkins.tails.boum.org/job/reproducibly_build_Tails_ISO_18655-zstd-squashfs-simple/1/console
  • automatically started test suite
    • https://jenkins.tails.boum.org/job/test_Tails_ISO_stable/5803/console
  • manually started test suite
    • https://jenkins.tails.boum.org/job/test_Tails_ISO_21160-curl-socks5h/1/console