add thread details for declarative config

[zeitlinger]

Part of #14087

Blocked by #15178

Note: automatically also applies to spring starter

Alternative for #14564

• should we also use this approach when NOT using declarative config?

[Copilot]

Pull Request Overview

This PR adds support for configuring thread details (thread ID and thread name) as span attributes through declarative configuration in the instrumentation API. When enabled via configuration, an AttributesExtractor automatically adds thread information to spans created by instrumenters.

• Adds ThreadDetailsAttributesExtractor to InstrumenterBuilder to capture thread ID and name
• Integrates with declarative configuration under instrumentation/java/thread_details/enabled
• Adds comprehensive test coverage for both enabled and disabled states

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
InstrumenterBuilder.java	Implements thread details extraction logic and configuration parsing
AddThreadDetailsTest.java	Tests thread details functionality with parameterized enabled/disabled scenarios
build.gradle.kts	Adds test dependency for declarative configuration support

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