Default Grafana alert RuleQuery interval to 30s

[cawthorne]

Summary

• Add RuleQuery.Interval to observability-lib with a default of "30s".
• Set interval on Prometheus datasource query models (refId A) in newRuleQuery, so deployed Grafana alert rules no longer show 1s on the datasource step.
• Reuse a shared defaultRuleQueryIntervalMs constant for condition query defaults.
• Add TestNewAlertRule_DefaultRuleQueryInterval.

Companion to chainlink-observability#467, which sets rule group evaluation intervals and condition intervalMs in chainlink-observability. This PR covers the remaining alert rule model layer: the Prometheus query step (refId A).

Coverage

Layer	Owner
Rule group evaluation (Evaluate every)	chainlink-observability #467
Condition step intervalMs (B/C)	observability-lib + chainlink-observability #467
Datasource query model interval (ref A)	This PR

Test plan

• go test ./observability-lib/grafana/...
• After merge: bump observability-lib in chainlink-observability and verify ref A shows "interval": "30s" in generated alert JSON

[github-actions]

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[github-actions]

✅ API Diff Results - github.com/smartcontractkit/chainlink-common/observability-lib

✅ Compatible Changes (2)

grafana (1)

• DefaultRuleQueryInterval — ➕ Added

grafana.RuleQuery (1)

• Interval — ➕ Added

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[Copilot]

Pull request overview

Adds a default Prometheus query interval for Grafana alert rule query models to avoid generated rules showing a 1s datasource step by default, aligning the alert rule “refId A” query step with the intended 30s evaluation cadence.

Changes:

• Introduces RuleQuery.Interval with a default of "30s" and applies it in newRuleQuery for Prometheus datasource query models (refId A).
• Reuses a shared defaultRuleQueryIntervalMs constant for condition query intervalMs defaults.
• Adds a unit test validating the default interval is set on the Prometheus query model.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
observability-lib/grafana/alerts.go	Adds default rule query interval support and reuses a shared interval constant for condition query defaults.
observability-lib/grafana/builder_test.go	Adds coverage to ensure the Prometheus query model interval defaults to "30s".

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[github-actions]

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