[flexiglass] Disables KeyguardShowWhileAwakeInteractorTest if flexi on

The class under test doesn't support flexiglass.

Bug: 283121968
Test: not really tested. Reproduced the test failure locally, saw that
it's always because of asserts that check that SceneContainerFlag isn't
enabled, so slapped a big @DisableSceneContainer on the test class
Flag: EXEMPT test only change

Change-Id: I782662fe3db64925f507218f0c558c5782fa0e11