Preserve rotation transform if the app is in a playing transition

In case there is consecutive transitions, which will postpone display
orientation update. If the transform is cleared during transition,
the activity may be relaunched and the animation will look flickering.

Fix: 384402546
Flag: EXEMPT bugfix
Test: Launch a landscape activity which starts another
      landscape activity and finishes in its onCreate.
Change-Id: I96dc96aa43de5e1d18cd5b8cc9f62639cf0624e1