gh-38635: fixing most ruff PERF4 warnings in combinat
this is fixing most suggestions of `ruff check --select=PERF4` in the
combinat folder.
### :memo: Checklist
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- [x] The title is concise and informative.
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preview.
URL: https://github.com/sagemath/sage/pull/38635
Reported by: Frédéric Chapoton
Reviewer(s): Matthias Köppe
