[experiment] ci: try 1es-ubuntu-24.04-min for Linux jobs instead of disk cleanup

[Ahmed Muhsin (ahmedmuhsin)]

Experiment — not for merge as-is. Opened as a draft to get a CI signal.

What

Switch the two Linux CI jobs (emulated tests, docker integration tests) from 1es-ubuntu-22.04 to 1es-ubuntu-24.04-min, and drop the Free up disk space cleanup steps that #883 added. A df/du report step is kept so the run tells us the new image's baseline headroom.

Why

The 1es-ubuntu-22.04 image boots ~92% full on / (67G used of 73G), almost entirely from toolsets these jobs never touch — Android SDK and Haskell under /usr/local (~24G), pre-cached docker images (~12G), Swift/miniconda under /usr/share (~9.5G), CodeQL/PyPy in the tool cache (~6.7G). That left so little headroom that dotnet test filled the disk, the agent process aborted with exit 134, and ADO reported the job as canceled.

#883 worked around it by rm -rf-ing those toolsets at job start (/ 92% → 54%, ~28G freed), which has held: 17 of 18 nightly dev builds since have passed with zero cancellations.

That workaround is still deleting things out from under a hosted image, which is fragile — it silently breaks if paths move in a future image. If the -min image ships lean enough, we can drop the cleanup entirely and rely on the image instead.

What to look for

1. Do the jobs still provision? -min images carry fewer preinstalled toolsets, so the likely failure mode is a missing dependency (Maven, preinstalled JDKs for JavaToolInstaller, docker, Python) rather than disk.
2. The Report disk space step output — how much free space does -min actually start with?

If it provisions cleanly with comfortable headroom, the follow-up is to drop the cleanup steps for good. If it needs extra tool installs, we compare that cost against keeping the rm -rf.

Scope

CI only, Linux only. Untouched: the Windows jobs, java-version-check.yml, and the official run-e2e-tests-linux.yml — those stay on 1es-ubuntu-22.04 until this experiment reports back.