v.21.2Improvements

Docker Image Improvements for ClickHouse Server Entrypoint

Docker image: several improvements for clickhouse-server entrypoint. #18954 (filimonov).
Improved the clickhouse-server Docker image entrypoint with several enhancements.

Why it matters

To enhance the startup process and usability of the clickhouse-server Docker image, making it more robust and user-friendly during container initialization.

How to use it

Users benefit from these improvements automatically by using the updated clickhouse-server Docker image; no additional configuration is required.