fix(go.d): unify histogram bucket dimension names

[ilyam8]

Summary

Test Plan

Additional Information

For users: How does this change affect me?

---

Summary by cubic

Unifies histogram bucket dimension names to the bare le value (e.g., 0.1, +Inf) across chartengine autogen and template paths, ordered numerically with +Inf last. Removes the bucket_ prefix for consistent heatmap dimensions and clearer docs/tests.

• Refactors

  • chartengine autogen sets dimensionName to the le value; tests and Prometheus histogram golden updated.
  • Docs updated in chartengine/README.md, charttpl/README.md, and SKILL to describe naming and ordering.

• Migration

  • If you reference bucket dimension names (dashboards, alerts, overrides), replace bucket_<value> with <value>.

^{Written for commit 834547d. Summary will update on new commits.}

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[cubic-dev-ai]

No issues found across 7 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

Architecture diagram

sequenceDiagram
    participant Prometheus as Prometheus Target
    participant Collector as go.d Prometheus Collector
    participant Metrix as metrix (ReadFlatten)
    participant Autogen as chartengine autogen
    participant Tpl as charttpl template
    participant Charts as Netdata Charts

    Note over Prometheus,Charts: Histogram bucket dimension naming flow

    Collector->>Prometheus: scrape /metrics
    Prometheus-->>Collector: histogram metrics (e.g., http_requests_duration_seconds_bucket{le="0.1"})
    Collector->>Metrix: ReadFlatten(metrics)
    Metrix-->>Collector: []FlattenedMetric (each with label le="0.1")
    Note over Collector: bucket metrics are non‑cumulative range totals

    alt Autogen path
        Collector->>Autogen: buildHistogramBucketAutogenRoute(metric)
        Autogen->>Autogen: chartID = metric.name + labels (excluding le)
        Autogen->>Autogen: dimensionName = le value (e.g., "0.1")
        Note right of Autogen: NEW: dimensionName no longer "bucket_" + upperBound
        Autogen-->>Collector: autogenRoute{dimensionName: "0.1", ...}
        Collector->>Charts: create chart with dimensions ["0.1", ..., "+Inf"]
    else Template path
        Collector->>Tpl: apply chart template
        Tpl->>Tpl: infer bucket dimensions from metrix labels
        Tpl->>Tpl: dimensionName = le value (bare)
        Note right of Tpl: NEW: template also uses bare le (documented)
        Tpl-->>Collector: resolved chart dimensions
        Collector->>Charts: create chart with dimensions ["0.1", ..., "+Inf"]
    end

    Note over Charts: Dimensions ordered numerically, +Inf last

    alt Example dimension list
        Charts->>Charts: ["0.1", "0.5", "1", "2", "10", "+Inf"]
    end

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_{Re-trigger cubic}