refactor(test): clean up GEPA ReAct test comments and improve docstrings

- Remove redundant helper functions (5 feedback → 1 simple_feedback)
- Consolidate verbose docstrings with clear descriptions
- Remove unnecessary inline comments
- Improve file-level docstring explaining bug fix and test coverage
- Fix whitespace linter warnings (9 auto-fixed)
- Reduce from 1054 to 975 lines (7.5% smaller)

All 8 tests passing

Author: Ju-usc