Fix an issue where insets were double subtracted when sizing taskview

getExpandedViewContainerPadding already accounts for the insets when
calculating the padding around the bubble expanded view.

mPositionRect is the rect that accounts for the insets, so when
using it in combo with getExpandedViewContainerPadding, we'd subtract
any insets twice. mScreenRect does not account for the insets, so
we should use that here instead.

Test: m CtsVerifier and ran through bubble test cases
Test: atest BubblePositionerTest
Test: manual - look at expanded bubbles in portrait / landscape on
               folded / unfolded device (with and without insets),
               and on large screen tablet.
Bug: 318308404
Bug: 322430409
Change-Id: Id96e0564321d9ba1ed554a2ca6050adf09021ba2