Add host_name config parameter to avoid hostname resolution in ON CLUSTER DDL queries

Why it matters

This feature addresses the issue where cluster definition changes can cause hostname resolution delays, potentially leading to query queues getting stuck. By allowing users to specify hostnames explicitly, it improves stability and reliability when executing distributed DDL commands and managing Replicated databases.

How to use it

Set the <host_name> parameter in the ClickHouse configuration file to the desired hostname or IP address. This prevents automatic hostname resolution during ON CLUSTER DDL queries and for Replicated database engines, ensuring smoother cluster operations.