Add support for configuring Patroni REST API request queue size

[chobostar]

This introduces an optional request_queue_size parameter for the Patroni REST API, with a default value of 5. It controls the TCP socket queue size, and once full, additional requests will receive a "Connection denied" error.

Motivation

The proposed change addresses an availability issue in Patroni's REST API caused by the low default TCP accept queue size (5), which can lead to frequent listen queue overflows under high load, such as HAProxy health checks. By introducing a configurable request_queue_size option, this fix ensures greater scalability and stability for high-traffic environments while maintaining backward compatibility with the default settings

References

patroni/patroni#2643

https://patroni.readthedocs.io/en/latest/yaml_configuration.html#rest-api

request_queue_size: (optional): Sets request queue size for TCP socket used by Patroni REST API. Once the queue is full, further requests get a “Connection denied” error. The default value is 5.

[vitabaks]

Ok, thanks!