Apply max_concurrent_queries config changes at runtime without restart

Why it matters

This feature allows database administrators to dynamically adjust the maximum number of concurrent queries handled by ClickHouse, improving operational flexibility and reducing downtime. It solves the problem of having to restart the server to apply concurrency limit changes, thereby enhancing system availability and responsiveness.

How to use it

Modify the max_concurrent_queries setting in the configuration file or via configuration reload commands. The changes will be applied immediately at runtime without needing to restart the ClickHouse server.