PIPE-3239: Clean up bandpass heuristics logging and simplify helper functions
- Switch to lazy logging in do_bandpass for bpsolint_mode heuristics
- Simplify _compute_median_snr, ensuring immediate subtable cleanup and typed docstrings
- Normalize band casing in is_high_frequency_band and deduplicate HIGH_BANDS
- Log warning and debug traceback if exception occurs during SPW frequency lookup
- Add unit test for exception logging in bandpass_test.py