Root cause: ag/10614943 removed the resources, so each of item
values is hard coded. This broke the overlay. This CL adds the
resource back so the overlay can work.
Bug: 159301925
Test: make RunSettingsRoboTests ROBOTEST_FILTER=\
EnabledNetworkModePreferenceControllerTest (PASS)
Change-Id: Id5ad2fdd0a87586136e4a26d2e44cf5278df5d9d