Remove unused JSONSyncCongiBDObserver
Remove unused JSONSyncCongiBDObserver

It's not used for this PR. If needed, it will be added along with the
external backup configs.

meganz/sdk,Acidburn0zzz/sdk,Acidburn0zzz/sdk,meganz/sdk,meganz/sdk,Acidburn0zzz/sdk,meganz/sdk,meganz/sdk,Acidburn0zzz/sdk,meganz/sdk,meganz/sdk,Acidburn0zzz/sdk,Acidburn0zzz/sdk,Acidburn0zzz/sdk,Acidburn0zzz/sdk