Consider display cutout in PopupWindowTest

The deprecated stable insets is returning the system bar insets. The
test is trying to avoid the pop-up window overlapping with any system
insets, including the display cutout. Make use of the latest API to make
sure the display cutout is considered correctly, and moving away from
the deprecated API.

Without this change, CTS on GSI will fail on felix landscape folded
state.

Test: PopupWindowTest with CTS on GSI, with felix
Bug: 392947504
Flag: EXEMPT bugfix
Change-Id: I486eee1afe5af5f928d4e7dce6e91e7ed7351b74