Additional unit tests in light of better tracing refactor

[ns-rse]

#932 refactored tracing and introduced nodestats.

In doing so a bunch of unittest skeletons were created for methods/functions but tests not developed.

These are currently marked as @pytest.mark.skip(reason="Awaiting test to be written 2024-10-14")

Affected test files are...

• tests/tracing/test_disordered_tracing.py
• tests/tracing/test_nodestats.py
• tests/tracing/test_ordered_tracing.py
• tests/tracing/test_skeletonize.py