Add RequiresDevice annotation to e2e tests that need a device

This allow us to better filter which tests we should run on each target (CF and devices) without requiring a second test_mapping tag

Context: go/wm-infra-optimize

Test: atest Flickertests WMShellFlickerTests
Flag: TEST_ONLY
Bug: 311643481
Change-Id: I43481f8a26de1461ac2f1162d84064aaa0df9f3d