By the way of D8959, performed some minor cleanups in blob codebase.
- Recently noticed that aws_sdk_{dynamodb,s3}::Client already have Arc inside, so we don't need to wrap it with Arc again.
- Also deleted unnecessary aws_types dependency. The type we're using is already included in aws_client. > It probably wasn't in the past and that's why it was added, but now it's not needed anymore.
Plus some very minor fixes to fix Clippy warns.
Depends on D8959