motor_ramp: set fmu in test mode and cleanup (#11249)
motor_ramp: set fmu in test mode and cleanup (#11249)

and restore pwm min after test

dagar/Firmware,krbeverx/Firmware,PX4/Firmware,krbeverx/Firmware,krbeverx/Firmware,dagar/Firmware,acfloria/Firmware,dagar/Firmware,PX4/Firmware,PX4/Firmware,krbeverx/Firmware,krbeverx/Firmware,PX4/Firmware,acfloria/Firmware,krbeverx/Firmware,krbeverx/Firmware,PX4/Firmware,PX4/Firmware,acfloria/Firmware,acfloria/Firmware,PX4/Firmware,dagar/Firmware,acfloria/Firmware,dagar/Firmware,acfloria/Firmware,dagar/Firmware,acfloria/Firmware,dagar/Firmware