Sub: Even if the baro is normal, MP still reports "Bad Baro Health" error.

The MP has been reporting an error of "Bad Baro Health", but my baro is normal and the value is displayed normally, as shown in the following figure: [Bad Baro Health](https://drive.google.com/file/d/1dr5zwJtzijNrvFKg2EO3n7j7V7Cm_ibD/view)

I think i have already discovered the bug. [the two lines of code inside 'if'](https://github.com/ArduPilot/ardupilot/blob/Sub-4.1/ArduSub/GCS_Sub.cpp#L51) do not work because they have already been executed in [baro status](https://github.com/ArduPilot/ardupilot/blob/Sub-4.1/libraries/GCS_MAVLink/GCS.cpp#L164). At the same time, if i don't have a depth sensor, this error will continue to prompt because of this [if](https://github.com/ArduPilot/ardupilot/blob/Sub-4.1/ArduSub/GCS_Sub.cpp#L55).

**Version**
Sub-4.x

**Platform**
[ ] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ ] Rover
[ * ] Submarine

Start in ArduSub/GCS_Sub.cpp around lines 51-55 and compare its barometer-status handling with libraries/GCS_MAVLink/GCS.cpp around line 164. Reproduce the report on Sub-4.x with a normal barometer and no depth sensor, then trace why the health check still reports "Bad Baro Health." Done means a healthy barometer no longer produces the erroneous message in that setup, with relevant tests or verification run.

Written by the indexing model from the issue text.