[core] Support empty dirs cleaning without bucket sub dir in orphan files cleanup

[XiaoHongbo-Hope]

Purpose/Problem

Currently, OrphanFilesClean does not clean empty partition directories with no bucket subdirectories, causing a lot of empty dirs left.

Example Scenario:
Note: All belows are empty dirs.

Before:

table_root/
├── part1=0/
│   ├── part2=a/
│   │   ├── bucket-0/      ← cleaned
│   │   └── bucket-1/      ← cleaned
│   └── part2=b/           ← NOT cleaned
└── part1=1/               ← NOT cleaned

After:

table_root/
├── part1=0/
│   ├── part2=a/
│   │   ├── bucket-0/      ← cleaned
│   │   └── bucket-1/      ← cleaned
│   └── part2=b/           ← cleaned
└── part1=1/               ← cleaned

Tests

OrphanFilesCleanTest
RemoveOrphanFilesActionITCaseBase
LocalOrphanFilesCleanTest

API and Format

Documentation

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