Increase max_concurrent_queries from 100 to 1000 and enable concurrency control by default

Increase the default value of max_concurrent_queries from 100 to 1000. This makes sense when there is a large number of connecting clients, which are slowly sending or receiving data, so the server is not limited by CPU, or when the number of CPU cores is larger than 100. Also, enable the concurrency control by default, and set the desired number of query processing threads in total as twice the number of CPU cores. It improves performance in scenarios with a very large number of concurrent queries. #46927 (Alexey Milovidov).