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.
DataPartsVector & broken_parts_to_detach,
    DataPartsVector & duplicate_parts_to_remove,
    ThreadPool & pool,
    size_t num_parts,
    std::queue<std::vector<std::pair<String, DiskPtr>>> & parts_queue,
    bool skip_sanity_checks,
    const MergeTreeSettingsPtr & settings)
{
    
    pool.setMaxThreads(std::min(static_cast<size_t>(settings->max_part_loading_threads), num_parts));
    size_t num_threads = pool.getMaxThreads();
    std::vector<size_t> parts_per_thread(num_threads, num_parts / num_threads);
    for (size_t i = 0ul; i < num_parts % num_threads; ++i)
        ++parts_per_thread[i];
    
    
    std::vector<std::vector<std::pair<String, DiskPtr>>> threads_parts(num_threads);
    std::set<size_t> remaining_thread_parts;
    std::queue<size_t> threads_queue;
    for (size_t i = 0; i < num_threads; ++i)
    {
        remaining_thread_parts.insert(i);
        threads_queue.push(i);