`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 (!ignored_part_uuids)
        const_cast<PartUUIDsPtr &>(ignored_part_uuids) = std::make_shared<PartUUIDs>();
    return ignored_part_uuids;
}
AsynchronousInsertQueue * Context::getAsynchronousInsertQueue() const
{
    return shared->async_insert_queue.get();
}
void Context::setAsynchronousInsertQueue(const std::shared_ptr<AsynchronousInsertQueue> & ptr)
{
    using namespace std::chrono;
    if (std::chrono::milliseconds(settings.async_insert_busy_timeout_ms) == 0ms)
        throw Exception("Setting async_insert_busy_timeout_ms can't be zero", ErrorCodes::INVALID_SETTING_VALUE);
    shared->async_insert_queue = ptr;
}
void Context::initializeBackgroundExecutorsIfNeeded()
{
    auto lock = getLock();
    if (shared->are_background_executors_initialized)
        return;
    const auto & config = getConfigRef();
    size_t background_pool_size = 16;
    if (config.has("background_pool_size"))
        background_pool_size = config.getUInt64("background_pool_size");
    else if (config.has("profiles.default.background_pool_size"))
        background_pool_size = config.getUInt64("profiles.default.background_pool_size");
    size_t background_merges_mutations_concurrency_ratio = 2;
    if (config.has("background_merges_mutations_concurrency_ratio"))