Fixes #5054 by removing chinook's turn before landing and increasing ascend/descend speed

Allows for any helicopter to enable or disable the turn before landing
but sets it to default off for the chinook.  (may be desireable for
single player missions visual effect like Allies01?)  Also gives the
chinook a faster ascend/descend speed.  Fixes #5054
Merge pull request #5834 from Squiggles211/heli-turn

Increase Chinook landing speed and removed turn before landing.