Use the same animation setup in InsetsController for rounded corners

Uses the same animation setup in InsetsController when animate rounded
corners with insets changed. Also remove divider bar expanding animation
to prevent it overlapping with rounded corners and stage outline.

Bug: 200850654
Bug: 196272915
Test: atest WMShellUnitTests
Test: manul check the behavior of rounded corners when
      expanding/collapsing task bar.
Change-Id: I00449e1c25ca717305be7be9704f5805667adf45