sage: don't test for Cython source code in tracebacks (temporarily)

[collares]

Motivation for this change

To emit better tracebacks, IPython 8 (#154969) parses Python files using the ast module (via the stack_data package). Since Cython is a superset of Python, this results in no Cython code being printed in tracebacks. Fixing this properly is tracked in alexmojaki/stack_data#21, but for now we just disable the corresponding test. An alternative would be to revert IPython's IPython/core/ultratb.py, but this would need to be Sage-specific (since it would worsen tracebacks for pure Python code).

Sage tracks the IPython 8 upgrade at https://trac.sagemath.org/ticket/33170, a ticket which also includes two minor test changes. I added those to this PR as well.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 22.05 Release Notes (or backporting 21.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[collares]

Thanks for merging! This will be a temporary fix indeed, since upstream IPython just fixed this properly. But the fix will have to go through staging, so it's great to have this one merged already.

[collares]

#160031 (targeting staging) removes this patch.