Move docs workflows to elastic/docs-actions

[Mpdreamz]

Summary

Moves our docs CI/CD workflow logic from elastic/docs-builder to
elastic/docs-actions.
elastic/docs-builder has grown in scope; elastic/docs-actions lets the
docs team push updates to the @v1 tag independently without coupling to
the broader builder tooling.

The new setup follows GitHub's recommended two-phase workflow approach:
all required checks on pull requests now run with read-only access only.
Preview deployments and PR comments happen in a separate phase triggered
after the required check completes.

Replaces preview-build.yml and docs-cleanup.yml with three new workflow
files: docs-build.yml, docs-deploy.yml, and docs-preview-cleanup.yml.

Preview deployments for forks:
Preview deployments are not available for fork PRs by default. If you are an
Elastic employee working from a fork, previews will work once your Elastic
GitHub organization membership is set to Public:

1. Go to https://github.com/orgs/elastic/people and find your name

2. Open the visibility dropdown next to your name and select Public

   Or: GitHub profile -> Organizations -> Elastic logo -> set visibility
   to Public.

Contributors outside Elastic will still get build validation feedback on
their PRs -- only preview deployments are skipped.

Post-merge

• Update branch protection rules to require docs-build instead of
  preview-build (if applicable)

cc @elastic/ingest-docs

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 7d07d299-adfe-4582-9471-29dff41bdbb5

📥 Commits

Reviewing files that changed from the base of the PR and between 3c2055c and 8269c78.

📒 Files selected for processing (4)

• .github/workflows/docs-build.yml
• .github/workflows/docs-cleanup.yml
• .github/workflows/docs-deploy.yml
• .github/workflows/docs-preview-cleanup.yml

💤 Files with no reviewable changes (1)

• .github/workflows/docs-cleanup.yml

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📝 Walkthrough

Walkthrough

The GitHub Actions workflow configuration migrates from elastic/docs-builder reusable workflows to elastic/docs-actions@v1. The docs-build.yml workflow is refactored with updated trigger events (explicit pull_request types replacing pull_request_target) and a renamed job (build replacing docs-preview), along with simplified permissions. The docs-cleanup.yml workflow is removed entirely. Two new workflows are introduced: docs-deploy.yml triggers on docs-build completion and handles deployment, while docs-preview-cleanup.yml triggers on pull request closure and manages cleanup operations.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch migrate/docs-actions-workflows

• 🛠️ Update Documentation: Commit on current branch
• 🛠️ Update Documentation: Create PR

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