Create leveldb instance for internal volume

Level db instance connection setup will be done on volume attachement.
Since there is no fuse daemon thread for internal volume, level db
instance for internal volume will be created when external primary
volume is attached. Changes are behind device config flag
"stablise_volume_internal".

Test: Verified leveldb connection via logs
Bug: 239414704
Change-Id: I9a30ad122c84f06011182ac31a08146ec449c86c
6 files changed