Propagate trace context across Guidewire WSI SOAP worker threads

[ValentinZakharov]

What Does This Do

Adds a guidewire instrumentation so outbound SOAP calls keep their trace context.

Guidewire runs every SOAP call on its own raw thread (AsyncResponseImpl$WebserviceInvocationThread, shown as "WSI-Invocation"). We grab the current context when that thread is created and restore it when it runs, so the SOAP http.request span stays attached to its parent instead of starting a new trace

Motivation

The agent propagates context for thread pools, but not for a plain new Thread().start() - which is exactly how Guidewire makes SOAP calls. So the SOAP spans lost their parent (parent_id=0).
We can't instrument java.lang.Thread directly (it's on the agent's ignore list and loads before the agent), so we instrument Guidewire's own thread subclass instead

Additional Notes

• Self-contained: it both captures (in the constructor) and re-activates (in run()), so it works on its own. If the default runnable instrumentation also wraps run(), that's safe - the context is only consumed once.
• Narrow match: only Guidewire's WSI worker (AsyncResponseImpl$… that extends Thread). Normal thread-pool workers are not touched.
• Verified on three customer profiles (PolicyCenter, BillingCenter, Commercial-Lines PolicyCenter) - same class everywhere.
• New config: DD_TRACE_GUIDEWIRE_ENABLED (on by default)

Contributor Checklist

• Format the title according to the contribution guidelines
• Assign the type: and (comp: or inst:) labels in addition to any other useful labels
• Avoid using close, fix, or any linking keywords when referencing an issue
  Use solves instead, and assign the PR milestone to the issue
• Update the CODEOWNERS file on source file addition, migration, or deletion
• Update public documentation with any new configuration flags or behaviors
• Once approved, use merge queue to merge the PR

Jira ticket: [PROJ-IDENT]

[dd-octo-sts]

❌ New Groovy Files Detected

Please avoid introducing new .groovy files to this repository.

• dd-java-agent/instrumentation/guidewire/src/test/groovy/WsiAsyncResponseInstrumentationTest.groovy

Instead, rewrite the new file(s) in Java / JUnit. See the How to Test With JUnit Guide for more details.

If this PR needs an exception, add the tag: override groovy enforcement label to bypass this workflow.

[datadog-prod-us1-5]

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 56.06% (-1.87%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 71e353f | Docs | Datadog PR Page | Give us feedback!}