gh-36600: Support giac 1.9.0-67
The function `gb_giac()` is less noisy, so we adjust doctests in a way
they accept the noisy version (old giac) but don't fail with the silent
version (new giac).
### :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/36600
Reported by: Gonzalo Tornaría
Reviewer(s): Michael Orlitzky
