`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 (shutdown_called)
            return;
        shutdown_called = true;
        
        
        
        if (external_dictionaries_loader)
            external_dictionaries_loader->enablePeriodicUpdates(false);
        if (external_user_defined_executable_functions_loader)
            external_user_defined_executable_functions_loader->enablePeriodicUpdates(false);
        if (external_models_loader)
            external_models_loader->enablePeriodicUpdates(false);
        Session::shutdownNamedSessions();
        
        if (backups_worker)