v.24.8Improvement

Added Logs and Metrics for Rejected Connections Due to Resource Limitations

Added logs and metrics for rejected connections (where there are not enough resources). #66410 (Alexander Tokmakov).
Added logging and metrics for connections rejected due to insufficient resources in ClickHouse.

Why it matters

This feature helps users identify and monitor scenarios where new connections are refused because the server lacks sufficient resources. It improves observability and aids in diagnosing and managing resource limitations to ensure better system reliability and performance.

How to use it

The feature is enabled by default in the server. Users can monitor rejected connection events through the newly added logs and metrics. These can be accessed via the system logs and metrics endpoints without additional configuration.