Allow More Threads for Kafka Engine

Why it matters

This feature addresses the limitation of the Kafka engine being restricted to fewer threads, which can hinder throughput and parallel processing. By enabling more threads, it improves the performance and scalability of consuming Kafka topics in ClickHouse.

How to use it

Users can enable this feature by configuring the Kafka engine to use multiple threads through the appropriate table engine settings, increasing the kafka_num_consumers or similar configuration parameters to specify the desired number of consumer threads.