Remove dependencies to LockscreenWallpaper

Stop calling anything from LockscreenWallpaper (in particular,
notificationMediaManager#updateMediaMetaData) if the config flag for
the lockscreen live wallpaper project is enabled.

This CL does not remove code, since it does not change any behaviour if
the config flag is disabled.

Test: atest CtsWallpaperTestCases
Test: atest CentralSurfacesImplTest
Test: atest SystemUITests:com.android.systemui.statusbar.NotificationMediaManagerTest
Bug: 253507223
Change-Id: I2d0940bf4afc3c3fa283ed0773197360862ee480