Fix the test failures for the new lock screen notifications settings page

Fix the old tests that fail when the new lock screen notifications
settings page flag is enabled.

Fix: 393631085
Flag: com.android.server.notification.notification_lock_screen_settings
Test: LockscreenNotificationMinimalismPreferenceControllerTest,
RedactNotificationPreferenceControllerTest,
ShowOnlyUnseenNotificationsOnLockscreenPreferenceControllerTest

Change-Id: I427ce675721c6d4df6451deebfcb6e4c06c72c37