Fix snapshot window jump due to top window has another cutout mode

That jumping is because the WindowFrame of top fullscreen window isn't
align with app main window. In core there only check app main
window's cutout for layout, so for snapshot starting window, it should
use app's main window's cutout instead of top opaque window.

Another reason there doesn't need to use getTopFullscreenOpaqueWindow
is because core won't ask to create snapshot starting window if the
size/orientation of snapshot isn't align with the window configuration,
so the SnapshotDrawerUtils will not needs to draw background and bars,
since the aspectRatioMismatch should always return false.

Bug: 341020277
Test: manual, create a second window for an activity, verify snapshot
starting window won't jump when hot launch the app from background.

Change-Id: I4c6b0ccacc79730552cbf9b4928b5c842f4feb1e