Set cutout mode to shortEdges on flicker

Use short edges on the flicker tests so that the test apps cover the full screen in both raven and in flame devices. With default cutout, some assertions will need to be updated to consider the letterbox layers, as well as app windows not covering the entire display

Bug: 209935473
Test: atest FlickerTests WMShellFlickerTests
Change-Id: Iaeabe2033adc2890605bbef7bce139569f402c4b