Improve the user experience around upgrades between versions for columnstore

This initiative aims to simplify and harden the upgrade process for MariaDB ColumnStore across major and minor versions. It focuses on improving reliability, automation, and user clarity & confidence.
Whether upgrading in-place a single node or across multiple nodes, we want a consistent, easy experience.

Key goals include:

• Robust pre-upgrade checks and validation tools
• Automated upgrade orchestration for multinode clusters
• Enhanced error handling and rollback support
• Consistent handling of upgrade & downgrade of metadata/catalogs
• Revamped documentation thats is simple and easy to understand

These improvements will help reduce downtime, minimize user intervention, and support a smoother lifecycle for ColumnStore in production environments.