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 (auto part = outdatePart(NO_TRANSACTION_RAW, part_name,  false))
        dropPartsImpl({part},  false);
    
}
void StorageMergeTree::dropPart(const String & part_name, bool detach, ContextPtr query_context)