add TaskBlock events for blocking intervals

[kaahos]

What does this PR do?:

Adds datadog.TaskBlock JFR events for blocking intervals such as LockSupport.park, Object.wait, monitor contention, including recording APIs used by dd-trace-java for instrumented blocking operations such as Thread.sleep.

Motivation:

This builds on paul.fournillon/wallclock-suppression (#560) by preserving visibility into blocked spans as explicit duration events.

Additional Notes:

This PR does not add the dd-trace-java instrumentation itself; Thread.sleep emission depends on that side calling the new profiler APIs. Monitor callback support is HotSpot-specific, and virtual-thread carrier attribution is avoided.

How to test the change?:

• ./.claude/commands/build-and-summarize :ddprof-test:testDebug -Ptests="*.wallclock.*TaskBlockTest"
• ./.claude/commands/build-and-summarize :ddprof-lib:gtestDebug

For Datadog employees:

• If this PR touches code that signs or publishes builds or packages, or handles
  credentials of any kind, I've requested a review from @DataDog/security-design-and-guidance.
• This PR doesn't touch any of that.
• JIRA: [JIRA-14354]

Unsure? Have a question? Request a review!

[dd-octo-sts]

CI Test Results

Run: #26892091993 | Commit: 4c6b502 | Duration: 12m 33s (longest job)

✅ All 32 test jobs passed

Status Overview

JDK	glibc-aarch64/debug	glibc-amd64/debug	musl-aarch64/debug	musl-amd64/debug
8	-	✅	-	-
8-ibm	-	✅	-	-
8-j9	✅	✅	-	-
8-librca	-	-	✅	✅
8-orcl	-	✅	-	-
11	-	✅	-	-
11-j9	✅	✅	-	-
11-librca	-	-	✅	✅
17	✅	✅	-	-
17-graal	✅	✅	-	-
17-j9	✅	✅	-	-
17-librca	-	-	✅	✅
21	✅	✅	-	-
21-graal	✅	✅	-	-
21-librca	-	-	✅	✅
25	✅	✅	-	-
25-graal	✅	✅	-	-
25-librca	-	-	✅	✅

Legend: ✅ passed | ❌ failed | ⚪ skipped | 🚫 cancelled

Summary: Total: 32 | Passed: 32 | Failed: 0

---

Updated: 2026-06-03 15:09:38 UTC

[kaahos]

@copilot review this PR

[Copilot]

@copilot review this PR

Reviewed and found a flaky assertion in NativeSocketTaskBlockTest: it required zero TaskBlock events globally, which can fail when an untraced socket op emits one. Fixed in d21e493 by asserting that no TaskBlock is emitted for the traced span specifically, and re-ran :ddprof-test:testDebug -Ptests="*.wallclock.*TaskBlockTest" successfully.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Populate ASGCT wall sample IDs before anchoring

When wallprecheck is used with the default ASGCT wall-clock engine, recordSample() returns without ever assigning ExecutionEvent::_sample_id (unlike the JVMTI/deferred/external paths), so this line records 0 as the anchor for the blocked run. The resulting TaskBlock.anchorSampleId cannot point back to the MethodSample that was kept for the run, breaking the reconstruction metadata for the common wall=...,wallprecheck=true configuration.

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