CI Build&Test: Show full logs, do not truncate

[mkoeppe]

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation and checked the documentation preview.

⌛ Dependencies

[github-actions]

Documentation preview for this PR (built with commit bd9d1a3; changes) is ready! 🎉
This preview will update shortly after each push to this PR.

[mkoeppe]

Unfortunately the annotations don't work because each line is prefixed by Docker buildx's decorations.

Example: https://github.com/sagemath/sage/actions/runs/9542020402/job/26296119606#step:13:680

[kwankyu]

Unfortunately the annotations don't work because each line is prefixed by Docker buildx's decorations

Fixed? Can I see the changed behavior somewhere?

[mkoeppe]

Not fixed, not fixable.
What I hoped to do there regarding annotations will have to be done in a different way, by having the Docker build succeed even when there is a build error, and then retrieving the logs from the container and printing them out, similar to what is done in CI Linux.

[mkoeppe]

For this PR, I have reduced the scope to just print out the log without truncating. This was good enough to debug #38224.

[kwankyu]

OK.

[kwankyu]

LGTM

[mkoeppe]

Thanks!