[flexiglass] Parameterize KeyguardUpdateMonitorTest to run with SceneContainerFlag

Also fix KeyguardUpdateMonitorTest so that tests pass when the
SceneContainerFlag is enabled

Fixes: 353955910
Test: atest KeyguardUpdateMonitorTest
Flag: com.android.systemui.scene_container
Change-Id: I1a2fc9c3cacfe0c337efdd3b9592a3f40a4933e8
1 file changed