Plane:adjust CTUN.Pitch to remove PITCH_TRIM

[Hwurzburg]

We have ATT.Pitch, CTUN.Pitch, XKF1.Pitch all reporting the same pitch with PITCH_TRIM added, so there are no two log lines that one can graph showing desired/nav pitch vs reported pitch to check if pitch tuning is closely matching to indicate good tune....

removing PITCH_TRIM_DEG bias from one would allow an easy graphical evaluation of Pitch tune....doing it in ATT is problematic since its in AHRS and spans vehicle types....modifying CTUN.Pitch is easy and only affects FW Plane...the other two pitch logs are unaffected.

This also aligns with HUD artificial horizon visual indication

[Georacer]

@Hwurzburg perhaps you'd like to take a look at #29067

I think it gets the same result as this one (have comparable pitch quantities) by following a complementary path.

[Hwurzburg]

I am against adding Pitch trim in desired to make it match pitch ..then when flying level the desired pitch no longer is zero ...zero should indicate the vehicle is level on its artificial horizon

[Hwurzburg]

okay, I think this is good now....here is a SITL log of a quadplane in all different flight modes with this logging now:

[IamPete1]

Change looks good, should we add a note to the log message documentation here?:

ardupilot/ArduPlane/Log.cpp

Lines 315 to 316 in 2cd3970

	// @Field: NavPitch: desired pitch
	// @Field: Pitch: achieved pitch

[Hwurzburg]

added...a bit long but prevents confusion I think

fixed, thanks!