Rotate splitscreen drawable by 90 when splitscreen is vertical.

If splitscreen will be vertical on the device/display, rotate the icon
so that it seems that way.

Bug: 407647118
Test: Manual. Rotate tablet screen vertically and see the icon updates.
Flag: EXEMPT bugfix
Change-Id: Id5dfc06f16cc6b22eba05fc468d92395a134b78a