Add Rust build cache cleanup to maintenance script:
- Add cleanup_rust_cache() function with cargo clean integration
- Check for cargo availability before attempting cleanup
- Show cache size before/after for visibility
- Add 'rust' subcommand for targeted Rust cache cleanup
- Include Rust cache in 'benchmarks' and 'all' cleanup operations
- Add aggressive cleanup support for Rust
- Update help text and disk usage display
- Update E2E tests for consolidated docker-compose.test.yml
- Remove references to obsolete logs-debug.yml
- Enhance test fixtures and utilities
- Improve integration test coverage for KMS, queue, scheduler
- Update unit tests for config constants and worker execution
- Modernize cleanup-status.sh with new Makefile targets
