For some reasons when we delete a MergeTree Part in atomic way something may go wrong - and leave the `delete_tmp_*` folder or it's part on disk. This may lead to a disk space consumption over time.

It's suggested to delete this folders at least at server start-up. Current solution with `clearOldTemporaryDirectories()` doesn't work because this method is called periodically from a thread without any locks or advisory on folders - it may cause the race conditions.
{
    if (!getSettings()->remove_empty_parts)
        return 0;
    size_t cleared_count = 0;
    auto parts = getDataPartsVectorForInternalUsage();
    for (const auto & part : parts)
    {
        if (part->rows_count != 0)
            continue;
        
        if (!part->version.getCreationTID().isPrehistoric() && !part->version.isVisible(TransactionLog::instance().getLatestSnapshot()))
            continue;
        LOG_TRACE(log, "Will drop empty part {}", part->name);
        dropPartNoWaitNoThrow(part->name);
        ++cleared_count;
    }
    return cleared_count;
}
void MergeTreeData::rename(const String & new_table_path, const StorageID & new_table_id)