Add round-robin support for clickhouse-benchmark

Why it matters

This feature allows clickhouse-benchmark to distribute queries in a round-robin manner across specified hosts and ports. It provides a more balanced load distribution during benchmarking and improves the accuracy of performance statistics when running tests on multiple nodes.

How to use it

Use clickhouse-benchmark with the round-robin option enabled to run benchmarks across multiple hosts/ports. The behavior is similar to the existing multi host/port run, but the statistics reporting is adjusted to reflect the round-robin distribution.