[8.17] (backport #8485) [ci] add github notification for CI steps

[mergify]

What does this PR do?

This PR adds GitHub commit status notifications for individual Buildkite CI steps in both bk.integration.pipeline.yml and integration.pipeline.yml. Specifically:

• Introduces github_commit_status notifications for each major group of integration tests, including:
  • Packaging
  • ESS stack provisioning
  • Extended runtime leak tests
  • Windows integration tests
  • Ubuntu integration tests
  • Debian integration tests
  • RHEL8 integration tests
  • Kubernetes integration tests
• Each CI group now reports its status back to GitHub with a distinct context name, improving visibility of individual step results directly in GitHub PRs and commits.

Why is it important?

Adding granular GitHub commit statuses for each CI step provides better visibility and traceability of the CI pipeline's health directly in GitHub. This allows:

• Easier identification of failing or flaky test groups.
• Faster debugging by directly linking failed Buildkite jobs to corresponding GitHub contexts.
• Improved developer experience by surfacing Buildkite statuses in the GitHub UI.

Checklist

• I have read and understood the pull request guidelines of this project.
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in ./changelog/fragments using the changelog tool
• I have added an integration test or an E2E test

Disruptive User Impact

None.

How to test this PR locally

• Trigger the Buildkite pipeline after merging.
• Observe that each CI group now updates the corresponding GitHub commit status context.

Related issues

N/A

---

This is an automatic backport of pull request #8485 done by Mergify.

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarQube

[elasticmachine]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 34ae863

Failed CI Steps

• x86_64:sudo: fleet

cc @pkoutsovasilis