Update the split layout while density changed

According to mDividerSnapAlgorithm, the density change results in the
position of the driver bar changed, but the split layout is changed
only in the legacy transition environment. This CL updates the split
layout when the display density changed.

Bug: 273430199
Test: atest SplitLayoutTests
      atest StageCoordinatorTests
Change-Id: I767c499494c3498de36c007c7d3f1a0c275f776b