chore: remove unnecessary black_box in divan and bencher compat layers
Apply the same optimization from PR 98 to both divan and bencher compat layers:
- Remove black_box around routine calls during measurement
- Only apply black_box to outputs after measurement ends
- Reduces stack usage and eliminates unnecessary memory operations
- Improves benchmark performance by avoiding artificial overhead
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Co-Authored-By: Claude <noreply@anthropic.com>