KIP-602 — Change default value for client.dns.lookup

Accepted Kafka 2.6 Client

Changes the default value of `client.dns.lookup` from `default` to `use_all_dns_ips` so clients automatically try all IP addresses returned by DNS before marking a hostname as unreachable. The previous default tried only the first IP address, causing connection failures when a hostname resolved to multiple IPs and the first IP was unavailable (e.g. during rolling restarts behind a DNS load balancer).

Details