HDHM repair mechanism can be improved to clean stale buckets

[artemananiev]

HDHM repair mechanism introduced in #18593 can be improved further. What it currently does it iterates over all buckets and all bucket entries and compares them with data from path to KV store. If a key entry doesn't match, it's removed from HDHM. In addition to that, we can also check bucket indices to make sure bucket index is not corrupted, i.e. an index entry pointing to bucket data location, where a bucket with a different ID is located. There should be no such buckets, but there have been bugs recently that could result in index corruption. See #18235 for details.