This almost reverts the change to SettingsActivity#doUpdateTilesList in ag/6140694
except that instead of setting enabled to true, we set it to whether
backup is activated for this user.
Bug: 124114084
Test: 1a) Set up secondary user
1b) See that there is no Backup option in Settings Homepage - System
1c) adb shell bmgr --user 10 activate true
1d) Backup option is now present
1e) adb shell bmgr --user 10 activate false
1f) Backup option isnt there again
Change-Id: I3f17aabee92bedc91386444c2f0aede696d0fd13
4d626f63ec