Align test suite with FT601 removal from radar_protocol.py:
- Replace FT601Connection with FT2232HConnection throughout
- Rewrite _make_data_packet() to build 11-byte packets (was 35-byte)
- Update data packet roundtrip test for 11-byte format
- Fix truncation test threshold (20 -> 6 bytes, since packets are 11)
- Update ReplayConnection frame_len assertions (35 -> 11 per packet)
57 passed, 1 skipped (h5py), 0 failed.