gh-37762: `dist.yml`: Download optional/experimental tarballs for GitHub Release assets
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- Fixes #37752, at least for the non-"huge" tarballs (we skip the "huge"
tarballs here).
- More options for `sage -package download` (a subset of what `sage
-package list` supports)
- Also remove some zombie package files
Test run: https://github.com/mkoeppe/sage/actions/workflows/dist.yml
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### :hourglass: Dependencies
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- Depends on #37099 (merged to resolve merge conflict)
URL: https://github.com/sagemath/sage/pull/37762
Reported by: Matthias Köppe
Reviewer(s): Kwankyu Lee, Matthias Köppe
