[Flexiglass] Fix NotificationLockscreenUserManagerTest

This cl updates the test's setUp() method to correctly mock the
DeviceUnlockedInteractor dependencies (mDeviceUnlockedInteractorLazy and
mDeviceUnlockStatusStateFlow) when SceneContainerFlag is enabled.
Specifically, it ensures that:
- mDeviceUnlockedInteractorLazy.get() returns the intended
mDeviceUnlockedInteractor mock.
- mDeviceUnlockStatusStateFlow.getValue() returns a default
DeviceUnlockStatus object.

Bug: 416716455
Flag: com.android.systemui.scene_container
Test: com.android.systemui.statusbar.NotificationLockscreenUserManagerTest
     Locally run this test and verity all the tests are passed with the
     `@EnableSceneContainer` anotation.
Change-Id: I8fccac6f60e701b5cff12d9f1c2db70de3ef7bf9