refactor: remove async remote write decode logic (#1631)

## Rationale
Deserialization is a CPU-intensive task, so introducing async does not
provide significant benefits. In addition, using async causes function
contagion issues. Therefore, it is necessary to remove the async decode
logic.


## Detailed Changes
- Remove `decode_async` interface
- Change the back-end object pool dependency from `deadpool` to
`object-pool`
- Change benchmark logic accordingly


## Test Plan
Manual test