improve(go.d/smartctl): add configurable concurrent device scanning

[ilyam8]

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[Copilot]

Pull Request Overview

This PR adds configurable concurrent scanning for devices in the smartctl collector to improve performance when monitoring many devices. Key changes include:

• Introducing the new concurrent_scans configuration in YAML, JSON, metadata, and schema.
• Updating documentation and examples to describe concurrent scanning behavior.
• Implementing concurrent scanning logic in the collector and adding corresponding test cases.

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

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File	Description
src/go/plugin/go.d/collector/smartctl/testdata/config.yaml	Added concurrent_scans field to YAML configuration.
src/go/plugin/go.d/collector/smartctl/testdata/config.json	Added concurrent_scans field to JSON configuration.
src/go/plugin/go.d/collector/smartctl/metadata.yaml	Updated metadata and examples to document concurrent scanning.
src/go/plugin/go.d/collector/smartctl/config_schema.json	Updated configuration schema to include concurrent_scans.
src/go/plugin/go.d/collector/smartctl/collector_test.go	Added a new test case for concurrent scanning devices.
src/go/plugin/go.d/collector/smartctl/collector.go	Set default ConcurrentScans value in the Collector configuration.
src/go/plugin/go.d/collector/smartctl/collect.go	Implemented concurrent scanning logic and merged results concurrently using a pool.

Comments suppressed due to low confidence (2)

src/go/plugin/go.d/collector/smartctl/collect.go:54

• The concurrent scanning is only enabled when more than one device is present. If a single device may still benefit from concurrent treatment in future scenarios, consider documenting this behavior or adjusting the condition.

	if c.ConcurrentScans > 0 && len(c.scannedDevices) > 1 {

src/go/plugin/go.d/collector/smartctl/collect.go:84

• Merging metrics with maps.Copy overwrites keys from previous devices if duplicated. Ensure that device-specific metric keys are unique or adjust the merging strategy to prevent potential data loss.

			maps.Copy(mx, tempMx)