Fix an issue where stack education and the stack weren't aligned

On rotation the stack position is updated using the relative stack
position based on the last resting position. This doesn't work well
with the user education which relies on the stack being in the
"default" position & updating to the relative position clobbers this.
This change updates it so that:

1 - when the stack user education is shown it always updates the
    stack to be in the default position
2 - if stack user education is showing, don't set the stack position

Bug: 223635730
Test: manual - rotate device with stack user education showing and
               make sure the stack is aligned with the education view
Change-Id: I232227aed29ceef060883ed60ed02563093a9bbb