Feature Request: use bulk file deletion for cleanup_old_files when appropriate

[dylanzal]

The cleanup_old_files maintenance function currently deletes files one at a time. For cloud storage this results in unnecessary network requests, increasing runtime and cloud service provider costs. If a bulk deletion interface is available on the target file system, it would make sense to use this instead. For example, the S3 API can delete 1000 objects in a single request. This is particularly relevant for applications with high write volumes and frequent compaction, where thousands of small files may be marked for deletion during a compaction step.