Fix build-and-summarize script and description

[rkennke]

What does this PR do?:
Fix the build-and-summarize script/description. The description should reference the project-based build-and-summarize script, not the per-user script. The script itself failed to launch the subagent at the end, because the environment inherited the whole parent env, including CLAUDECODE, which apparently causes the subagent to fail (at least here, claude 4.6).

Motivation:
Improve agentic workflow.

Additional Notes:
None

How to test the change?:
Tell Claude Code to build and test the project.

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-XXXX]

Unsure? Have a question? Request a review!

[dd-octo-sts]

CI Test Results

Run: #22348895285 | Commit: 6bf54ea | Duration: 15m 4s (longest job)

✅ All 40 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	-	✅	-	-
8-zing	✅	✅	-	-
11	-	✅	-	-
11-j9	✅	✅	-	-
11-librca	-	-	✅	✅
11-zing	✅	✅	-	-
17	✅	✅	-	-
17-graal	✅	✅	-	-
17-j9	✅	✅	-	-
17-librca	-	-	✅	✅
17-zing	✅	✅	-	-
21	✅	✅	-	-
21-graal	✅	✅	-	-
21-librca	-	-	✅	✅
21-zing	✅	✅	-	-
25	✅	✅	-	-
25-graal	✅	✅	-	-
25-librca	-	-	✅	✅

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

Summary: Total: 40 | Passed: 40 | Failed: 0

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Updated: 2026-02-24 11:57:06 UTC