Update transition region calculation.

Makes the following updates to how transition regions are calculated in
freeform:
- The fullscreen region now takes up 40% of the display width.
- All regions now have a thickness of 44 dp.

Bug: 350933509
Test: atest DesktopModeVisualIndicatorTest, manual
Flag: EXEMPT refactor
Change-Id: I4762e97f2dace4d149d0367201c146e71b8d3e85