Remove manual CHANGELOG.md process

[andrross]

The CHANGELOG.md file has been a source of merge conflicts and have still resulted in poor quality release notes. Release notes will now be generated from PR and commit metadata instead.

See #21045 for the auto-generated release notes for the 3.6 release.

Related Issues

Resolves #21071

Check List

• Functionality includes testing.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[github-actions]

PR Reviewer Guide 🔍

(Review updated until commit bb1ea66)

Here are some key observations to aid the review process:

🧪 No relevant tests

🔒 No security concerns identified

✅ No TODO sections

🔀 Multiple PR themes Sub-PR theme: Remove CHANGELOG tooling and file content Relevant files: .gitattributes .github/workflows/changelog_verifier.yml .github/workflows/dependabot_pr.yml CHANGELOG.md Sub-PR theme: Update documentation to remove CHANGELOG references Relevant files: CONTRIBUTING.md DEVELOPER_GUIDE.md AGENTS.md

⚡ Recommended focus areas for review Data Loss The existing CHANGELOG.md content (unreleased 3.x entries) has been completely removed and replaced with a short redirect message. Verify that all unreleased changelog entries have been properly migrated or preserved in the auto-generated release notes system before this change is merged. As of the 3.6 release [the CHANGELOG is no longer used][1] to generate release notes. [Use this PR search][2] to browse unreleased changes. [1]: https://github.com/opensearch-project/OpenSearch/issues/21071 [2]: https://github.com/opensearch-project/OpenSearch/pulls?q=sort%3Amerged-desc+is%3Apr+-label%3Askip-changelog+is%3Amerged+base%3Amain+

[github-actions]

✅ Gradle check result for d4c3f2f: SUCCESS

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.26%. Comparing base (66bc444) to head (bb1ea66).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #21083      +/-   ##
============================================
- Coverage     73.29%   73.26%   -0.03%     
+ Complexity    73188    73171      -17     
============================================
  Files          5921     5921              
  Lines        333798   333798              
  Branches      48124    48124              
============================================
- Hits         244659   244566      -93     
- Misses        69563    69692     +129     
+ Partials      19576    19540      -36     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[bowenlan-amzn]

Curious how was the example release note PR #21045 generated?
Is it some bot which maintainers trigger on demand?

[andrross]

Curious how was the example release note PR #21045 generated? Is it some bot which maintainers trigger on demand?

@bowenlan-amzn It's a jenkins job that the release manager kicks off as a part of the release process. Ultimately this python script orchestrates the job and this is the prompt sent to the LLM.

[andrross]

@peterzhuamazon Can you remove verify-changelog as a required workflow so that we can merge this?

[cwperks]

@peterzhuamazon Can you remove verify-changelog as a required workflow so that we can merge this?

done

[cwperks]

@andrross ironically this PR cannot be merged until the conflicts in the CHANGELOG are resolved >.<

[github-actions]

Persistent review updated to latest commit 35696a0

[github-actions]

✅ Gradle check result for 35696a0: SUCCESS

[github-actions]

Persistent review updated to latest commit bb1ea66

[github-actions]

✅ Gradle check result for bb1ea66: SUCCESS