We were manually converting ObjectKey fields to []byte to use it with SQL query but we can just implement Value method to convert it automatically. Change-Id: I6d346f4b59718e1e8ef37cd9f95e613b864b42cd
This avoids corrupting objects if reuploads and metadata updates happen concurrently.
It replaces UpdateMetadataObject that hasn't been used anywhere yet. Change-Id: I1b2131acd75924c487a1c3ca099674251c5c9b56