Fixed issue with wrong stack fullscreen state on configuration change

- No need to run TaskStack#updateBoundsAfterConfigChange if the stack
is fullscreen as the bounds will already be updated to when the display
content changed due to rotation.
- Correctly set mTmpRect2 that we are using to calculate the rotated
bounds to the current mBounds.

Bug: 28319277
Bug: 27870534
Change-Id: Ic3d9407b735210351c28297de79bf035909afcfe