`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`.
{
    if (!shared->cluster_discovery)
        return;
    shared->cluster_discovery->start();
}
void Context::setClustersConfig(const ConfigurationPtr & config, bool enable_discovery, const String & config_name)
{
    std::lock_guard lock(shared->clusters_mutex);
    if (config->getBool("allow_experimental_cluster_discovery", false) && enable_discovery && !shared->cluster_discovery)
    {
        shared->cluster_discovery = std::make_unique<ClusterDiscovery>(*config, getGlobalContext());
    }
    
    if (shared->clusters && isSameConfiguration(*config, *shared->clusters_config, config_name))
        return;
    auto old_clusters_config = shared->clusters_config;
    shared->clusters_config = config;
    if (!shared->clusters)
        shared->clusters = std::make_shared<Clusters>(*shared->clusters_config, settings, getMacros(), config_name);
    else
        shared->clusters->updateClusters(*shared->clusters_config, settings, config_name, old_clusters_config);
}
void Context::setCluster(const String & cluster_name, const std::shared_ptr<Cluster> & cluster)