Address review feedback: refactor to use dictionary and parametrize tests

- Refactor get_sample_short_name_by_md5() to use dictionary lookup for O(1) performance
- Add _MD5_TO_SHORT_NAME module-level constant for efficient lookups
- Refactor tests to use pytest.mark.parametrize for better readability
- Split tests into separate functions for different concerns
- Fix CHANGELOG: use @kamranulhaq2002 instead of email
- Update CHANGELOG: use PR #2802 instead of #TBD
- Apply code formatting (isort, black, ruff)

Addresses feedback from Gemini Code Assist bot review.

Author: kami922

CHANGELOG.md

@@ -50,7 +50,7 @@
 
 - ci: remove redundant "test_run" action from build workflow @mike-hunhoff #2692
 - dev: add bumpmyversion to bump and sync versions across the project @mr-tz
-- fixtures: add function to resolve sample shortened name by MD5 kamranulhaq2002@gmail.com #TBD
+- fixtures: add function to resolve sample shortened name by MD5 @kamranulhaq2002 #2802
 
 ### Raw diffs
 - [capa v9.2.1...master](https://github.com/mandiant/capa/compare/v9.2.1...master)