gh-37211: change verbosity in matrix2
as requested in zulip at sage days 125 : lowering the verbosity to level
2
### :memo: Checklist
- [x] The title is concise, informative, and self-explanatory.
- [x] The description explains in detail what this PR is about.
- [x] I have updated the documentation accordingly.
URL: https://github.com/sagemath/sage/pull/37211
Reported by: Frédéric Chapoton
Reviewer(s): Marc
