Fix grid layout problem after going back from split select

- Don't reset mFocusedTaskViewId when focused task become split, so it's reset properly when it's added back to RecentsView
- Moved applySplitScrollOffset to RecentsViewStateController to be called after mSplitHiddenTaskView is added back to RecentsView
- Update scroll after going back from split
- Don't reset mSplitHiddenTaskView's translation as it'll clear the grid translations

Test: manual
Bug: 181707736
Change-Id: I4bd204fc537ee520216f875b3eddf4dc94f7bfd8