test: clean up existing test files

- Update extractor_unit_tests.rs to remove duplicated language tests
- Simplify extractor_integration_tests.rs to reference new structure
- Remove redundant test code now organized in language modules

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: unhappychoice