#1665 Clear optional fetch response fields to avoid making clients try to bypass shotover

[justinweng-instaclustr]

This PR clears the optional fields FetchResponse::node_endpoints, PartitionData::preferred_read_replica and PartitionData::current_leader in the Fetch response processed by the KafkaSinkCluster process_responses() function . This is to avoid passing these values to the client which will make the client try to bypass shotover and connect to Kafka brokers directly.

Closes #1665

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #1677 will not alter performance

_{Comparing justinweng-instaclustr:1665-rewrite-fetch-responses-to-not-refer-to-real-brokers (228e594) with main (fdd7e6b)}

Summary

✅ 39 untouched benchmarks