chore: address release script

[kaahos]

What does this PR do?:

fixes check_not_stuck so that a missing release tag is treated as the expected state for a new release.

The check now uses git show-ref --verify --quiet with the complete tag reference and returns success explicitly when the tag does not exist or the release is a dry run.

Motivation:

With set -e, the previous git rev-parse ... || return propagated exit code 128 when the target tag did not exist. This aborted valid releases before tag creation.

Additional Notes:

Existing tags still trigger the intended “branch is stuck” failure. Using the complete refs/tags/... reference also ensures that only the exact tag is checked.

An end-to-end release dry run can only be executed after merging because minor-release workflows require remote main.

How to test the change?:

• bash -n .github/scripts/release.sh
• git diff --check origin/main...HEAD
• Verified check_not_stuck behavior:
  • Missing tag returns 0.
  • Existing tag returns 1 with the expected diagnostic.
  • Dry-run returns 0.

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 security review (run the dd:platform-security-review
  skill, or file a request via the PSEC review form).
  bewaire also runs automatically on every PR.
• 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: #29955864873 | Commit: fb3ed74 | Duration: 14m 54s (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

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Updated: 2026-07-22 20:59:39 UTC

[jbachorik]

Thanks!