sage

930d65e6 - gh-36308: using itertools.product more often

gh-36308: using itertools.product more often This replaces some uses of our `cartesian_product_iterator` by `itertools.product`, for better efficiency. ### :memo: Checklist - [x] The title is concise, informative, and self-explanatory. - [x] The description explains in detail what this PR is about. URL: https://github.com/sagemath/sage/pull/36308 Reported by: Frédéric Chapoton Reviewer(s): Marc Mezzarobba