Update dock stack create mode after rotation if dock side changed

On some devices (such as tablets) dock stack could be created on top,
but put to right after rotation. Dock create mode needs to be updated
in this case, otherwise when a new stack is attached to the display
(for example launch into now-cropped fullscreen stack),
attachDisplayContent() will use wrong dock mode to derive the bounds.

bug: 28942558
Change-Id: I83e66aeac94bd3f96c4b6a0a740acf76234bbe82