Update SplitContainer for non-finishing containers

If an app is split with an Activity from another process
by Activity Embedding feature, and is launched twice
with different orientations, there's a chance that
the app still shows in previous orientation at the second
launch even if the orientation is changed.

The root cause is that, the app goes back to background
before the secondary container receives its TaskFragmentInfo.

Also, there's no pendingActivities and #onActivityPostCreated
won't be invoked, and also #updateContainer to change its
layout, because the Activity is from other process.

Moreover, in #onTaskFragmentParentInfoChanged, updateContainer
is skipped because secondary container is empty(No pending activities,
and hasn't received its TaskFragmentInfo).

This CL fixes the issue by verifying if one or both containers are
finished instead.

fixes: 228906392
Test: atest SplitControllerTest
Test: manual - reproducible steps in bug

Change-Id: Ifba4b56c9225089776835aeeef7c4a13249b55bf