`DataTypeFactory::get` locks a mutex inside shared a context, there was a case when many threads were locked inside it

https://pastila.nl/?0043b3e6/c557368f4cf0eb87a3c6f2cc162bc693

It is not clear which thread locked the mutex for a long time. However, it may be possible to lock less inside `DataTypeFactory::get`.
{
    auto lock = getLock();
    if (!shared->distributed_schedule_pool)
    {
        size_t background_distributed_schedule_pool_size = 16;
        if (getConfigRef().has("background_distributed_schedule_pool_size"))
            background_distributed_schedule_pool_size = getConfigRef().getUInt64("background_distributed_schedule_pool_size");
        else if (getConfigRef().has("profiles.default.background_distributed_schedule_pool_size"))
            background_distributed_schedule_pool_size = getConfigRef().getUInt64("profiles.default.background_distributed_schedule_pool_size");
        shared->distributed_schedule_pool = std::make_unique<BackgroundSchedulePool>(
            background_distributed_schedule_pool_size,
            CurrentMetrics::BackgroundDistributedSchedulePoolTask,
            "BgDistSchPool");
    }
    return *shared->distributed_schedule_pool;
}
BackgroundSchedulePool & Context::getMessageBrokerSchedulePool() const