The --viewer path (tee MAVLink frames to UDP and enable the
HIL_STATE_QUATERNION/HIL_ACTUATOR_CONTROLS streams so Hawkeye could
render an SIH flight live) was never validated end to end: Hawkeye
never actually rendered from it. Rather than ship an unproven feature,
drop it.
Removes px4bench.attach_viewer_tee (and its function-local socket use),
the flight_mission --viewer/--viewer-port args, the viewer tee call and
the stream-enable block, and the now-unused --board-dev arg that only
fed those stream commands. The SIH flight logic, firmware gate,
storage/serial tests, and the arming gate are unchanged. README and the
bench testing docs page drop the Hawkeye section and all --viewer
mentions.
Signed-off-by: Ramon Roche <mrpollo@gmail.com>