gh-38523: CI Linux: Strip timestamps printed by docker buildkit
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- Example of GitHub workflow commands that take action again thanks to
stripping the timestamps: The folding of output seen in https://github.
com/mkoeppe/sage/actions/runs/10438847625/job/28906649046#step:11:3839
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### :hourglass: Dependencies
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URL: https://github.com/sagemath/sage/pull/38523
Reported by: Matthias Köppe
Reviewer(s): Kwankyu Lee
