[Feature] optimize clean orphan files

[chongchongxiao]

Search before asking

• I searched in the issues and found nothing similar.

Motivation

OrphanFilesCleanerImpl::GetUsedFiles executes serially. If there are many files, its performance is poor. This can be done in executor.

Solution

Each snapshot-related file can be read concurrently, so the snapshot is placed as a task in the executor for execution.

Anything else?

No response

Are you willing to submit a PR?

• I'm willing to submit a PR!