improve(go.d/sql): add per-query execution time charts

[ilyam8]

Summary

This PR adds query execution time charts to the generic SQL collector.

Every SQL query now exposes its own timing metric so users can understand the performance characteristics of their database queries.

Test Plan

Additional Information

For users: How does this change affect me?

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Summary by cubic

Adds per-query execution time charts to the SQL collector, exposing a “duration” metric per query to help spot slow statements. Also updates chart metadata and connection handling.

• New Features

  • Per-query timing charts (ms) for reusable and inline metric queries.
  • One chart per query_id with driver/query_id labels and a single “duration” dimension.
  • Timing metrics emitted via collectQueryTimingMetrics using buildTimingChartIDFromQueryID.

• Refactors

  • Renamed buildChartID to buildMetricChartID; added createMetricBlockChart with updated context and labels.
  • Split chart priorities; chart context now sql._.
  • openConnection(ctx) with PingContext respecting Timeout; conn max lifetime set to 10m.
  • Renamed QueryRowsCache to queryRowsCache; removed unused skipValues.
  • Fixed MySQL DSN link in metadata.

^{Written for commit 1bc9ca0. Summary will update automatically on new commits.}

[Copilot]

Pull Request Overview

This PR adds per-query execution time charts to the SQL collector, enabling users to monitor the performance characteristics of their database queries. Each SQL query now exposes its own timing metric measured in milliseconds.

• Adds timing metric collection for both reusable queries and metric-block inline queries
• Introduces dedicated query timing charts with driver and query_id labels
• Refactors type and function names for better consistency and encapsulation

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/go/plugin/go.d/collector/sql/query.go	Renamed QueryRowsCache to unexported queryRowsCache for better encapsulation; removed unnecessary zero-duration assignment for query references
src/go/plugin/go.d/collector/sql/collect.go	Added collectQueryTimingMetrics function to collect and expose query execution times; updated openConnection to accept context parameter; renamed chart building functions for clarity
src/go/plugin/go.d/collector/sql/charts.go	Added createQueryTimingChart function to create per-query timing charts; updated priority constants and chart labels to include driver information
src/go/plugin/go.d/collector/sql/collector.go	Removed unused skipValues field from Collector struct
src/go/plugin/go.d/collector/sql/metadata.yaml	Fixed malformed markdown link by removing extra opening parenthesis in DSN parameter documentation

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[cubic-dev-ai]

No issues found across 5 files