Consistent use of Final annotation for module-level constants

[oboehmer]

Context

During review of #657, it was noted that DEFAULT_TEST_TYPE in common/types.py lacks a Final annotation, while VALID_TEST_TYPES and BASE_CLASS_MAPPING in test_type_resolver.py do use Final.

Looking at the broader codebase, none of the constants in core/constants.py or other modules use Final — only test_type_resolver.py does. Adding Final to just DEFAULT_TEST_TYPE would widen rather than narrow the inconsistency.

Discussion

Should we:

1. Add Final to all module-level constants across the codebase (systematic, but potentially noisy)
2. Remove the existing Final annotations from test_type_resolver.py to match the rest of the codebase
3. Leave as-is — the value of Final for simple constants may not justify the annotation overhead

Factors to consider:

• mypy already catches most reassignment issues through other type checks
• Final adds value mainly for constants that could be confused with mutable variables
• Consistency within the codebase matters more than following a theoretical best practice

References

• PR feat(pyats): add tag-based filtering for pyATS tests #657 review item Bump actions/setup-python from 3 to 4 #1