Avoid intermediate orientation change

The onDescendantOrientationChanged in Task was used for reporting
requested orientation takes affect after display windowing mode
is changed. But when calling WMS#setWindowingMode, it will call
DC#reconfigureDisplayLocked that also updates orientation from
display so the task orientation can still propagate to display.

So just remove the invocation of onDescendantOrientationChanged
from task's config change. That prevents from reporting
intermediate orientation change when re-parenting multiple tasks
from multi-window to fullscreen.

Bug: 186657559
Test: TaskTests#testTaskOrientationOnDisplayWindowingModeChange
Change-Id: Ie722a4384829c2dab4ee4c35de6ffbbb4a0e4655