KafkaSinkCluster - add context to anyhow errors

[rukai]

This was very useful for tracking the cause of outgoing connection closed issues.

Before:

After:

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #1716 will not alter performance

_{Comparing rukai:kafka_sink_cluster_error_context (8f497e0) with main (13c7937)}

Summary

✅ 39 untouched benchmarks