Update expanded view drop target size

The drop target does not have uniform padding on all edges.
Update based on latest spec.

Bug: 388856523
Test: atest DesktopModeVisualIndicatorTest
Flag: com.android.wm.shell.enable_bubble_to_fullscreen
Change-Id: Iba46fe055e63ec978555330c63c4ecc5d8f24a21