Update bubble bar expanded view drop target size

Drop target should have 28dp corner radius and 24dp padding compared to
the expanded view size.

Bug: 331641352
Test: atest WMShellRobolectricTests:BubbleExpandedViewPinControllerTest
Test: atest WMShellMultivalentTestsOnDevice:BubbleExpandedViewPinControllerTest
Change-Id: I47b29df413d51b70df40e68b4ba36cdef00032ff
4 files changed