Fix activity does not relaunch after config change.

Fix two minor problems while refactoring.
- EnsureVisibleActivitiesConfigHelper doesn't apply
to activities. Wrong boundary.
- Full screen stack doesn't dump it's bounds to proto,
actually we should dump the bounds from FullConfiguration
since we should only care the final result.

Bug: 80414790
Bug: 149429752
Test: atest SplitScreenTests
Change-Id: I466867d1ec9c2e5227575f884cac85907a13faab