Maintain relative order of changes during CHANGE transits

Previously there was a specific fix for ordering during
CHANGE transit. However, it was too broad and caused order
to reverse for TO_BACK transitions.

This CL changes the logic a little to just put all changes
into the same z-order "strata" if the overall transition
isn't an open or close type. This maintains relative ordering
instead of trying to make assumptions.

Bug: 340128968
Bug: 283076194
Test: go "back" from one task to another via moveToBack
      (example is back from wallpaper settings to settings
       on a non-AE device).
Change-Id: I9d78062bd401893ec9a241ce72fb182040d9f06a
(cherry picked from commit fd582575)