Don't Allow wchc Operation for ClickHouse-Keeper

Why it matters

This feature prevents the use of the wchc four-letter command within ClickHouse Keeper. Four-letter commands are used for operational control and diagnostics, but wchc is disallowed to improve security and prevent unauthorized or unintended operations on the ClickHouse Keeper service.

How to use it

Users do not need to take any explicit action to enable this feature. It is automatically enforced in ClickHouse Keeper to block the wchc command from being executed.