Parameter metadata displayed does not match the firmware on vehicle

#### Issue details
While flying, I intended to set the THR_FS to 2. The full parameter list indicated that 2 was a valid value to set, and the response from mission planner is that the parameter setting was successful. The behavior on the plane, however, did NOT change because it was running 4.0.6 beta 1 that could not set this parameter. The wiki and many other sources can pull the correct parameter descriptions, I would also expect Mission Planner to do the same.

#### Version
1.3.74

#### Platform
[X] All
[ ] AntennaTracker
[ ] Copter
[ ] Plane
[ ] Rover
[ ] Sub

#### Airframe type
Plane

#### Hardware type
Cube

Start by tracing how Mission Planner obtains and displays parameter metadata, then compare it with the firmware-supported definition for THR_FS in ArduPilot 4.0.6 beta 1. Check the full parameter list and the setting response path. Done means Mission Planner does not present unsupported values and accurately reflects whether the firmware accepted the parameter.

Written by the indexing model from the issue text.