Multicopter althold altitude adjustment manual climb rate fix

[breadoven]

PR fixes a problem with incorrect manual climb rates during altitude adjustment where the climb rates don't match the max manual climb rate setting as mentioned in #10660.

It should be noted that this PR will supersede #11241 which doesn't appear to fix the issue. Rather than correct that PR it seems easier to raise this new PR given it refactors the original method used (it removes the use of applyDeadbandRescaled which probably caused the problem in the first place).

Testing shows this fix works regardless of the nav_mc_althold_throttle setting giving the correct max climb and descent rates at max and min throttle stick.

[Jetrell]

Can you clear this up for me..
I though a commit you added in #11322 fixed this. From the tests I did last week ?
Or is this to fix it after #11241 was merged and broke it again ?

[breadoven]

Can you clear this up for me.. I though a commit you added in #11322 fixed this. From the tests I did last week ? Or is this to fix it after #11241 was merged and broke it again ?

#11322 is nothing to do with this ... separate thing entirely.

#11241 was never merged.

I might need to double check this PR because I tested it using the raw stick position rather than using rcCommand[THROTTLE]. Didn't think it would matter and would work itself out but checking again rcCommand[THROTTLE] doesn't behave as you'd expect during Althold. The different throttle references are a bit of a pain at times.

[Jetrell]

#11322 is nothing to do with this ... separate thing entirely.

I left a comment here after testing that PR #11322 (comment)
That was in response to a comment I left here

I'm not being argumentative. I'm simply trying to wrap my head around the changes. Being that I certainly noticed a difference in the manual climb rate control, between #11322 and #11270

[breadoven]

#11322 is nothing to do with this ... separate thing entirely.

I left a comment here after testing that PR #11322 (comment) That was in response to a comment I left here

I'm not being argumentative. I'm simply trying to wrap my head around the changes. Being that I certainly noticed a difference in the manual climb rate control, between #11322 and #11270

I think any improvement after #11322 was either due to some benefit of that PR (better velocity estimate) or just a coincidence. #11270 would have helped also but only if the GPS fix was poor. Neither of those PR was intended to fix the manual climb rate issue but they may have done by just generally improving the velocity estimates.

[breadoven]

Double checking using rcCommand[THROTTLE] and it seems to work as expected.