Remove IP label from DNS query metrics

[tpantelis]

Remove the destination_service_ip label to reduce metrics cardinality. Each unique IP creates a separate time series, leading to unbounded cardinality in dynamic environments with pod scaling and restarts. Service-level aggregation should be sufficient for monitoring use cases.

Summary by CodeRabbit

• Refactor
  • Simplified DNS query metrics by removing the destination service IP label. Metrics now track four dimensions instead of five.

[submariner-bot]

🤖 Created branch: z_pr2028/tpantelis/rem_ip_label
🚀 Full E2E won't run until the "ready-to-test" label is applied. I will add it automatically once the PR has 2 approvals, or you can add it manually.

[coderabbitai]

Walkthrough

The changes remove the destination service IP label from DNS query metrics across the CoreDNS plugin. The metric now tracks four labels instead of five: source cluster, destination cluster, destination service name, and destination service namespace.

Changes

Cohort / File(s)	Summary
DNS Query Metrics Simplification coredns/plugin/metrics.go, coredns/plugin/handler.go	Removed dstSvcIP parameter from incDNSQueryCounter function signature and updated the call site in getDNSRecord. Also removed the dstSvcIPKey constant and its corresponding label from the prometheus GaugeVec definition.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~5 minutes

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Remove IP label from DNS query metrics' accurately and concisely describes the main change across both modified files (handler.go and metrics.go), which consistently remove the IP-related parameter and label.
Actionable Comments Resolved	✅ Passed	No actionable comments (TODO, FIXME, XXX, HACK, NOTE) found in modified files; all code changes complete and consistent with PR objectives.

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No actionable comments were generated in the recent review. 🎉

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