Fix authoring repo on bundle products

[lcawl]

Summary

Fixes #4060

Details

products[].repo is now the authoring GitHub repo (same resolution as the bundle filename), not products.yml repository:.

Code

• BundleBuilder stamps the repo argument on every product. It no longer reads the product catalog.
• ChangelogBundlingService fills that argument with --repo / profile / bundle.repo, then GITHUB_REPOSITORY / git origin.
• Catalog lookup (GetProductsByRepositoryName, repository: cloud) is unchanged.

Tests and docs

• Unit tests in BundleBuilderPerProductRepoTests now expect authoring repo (including cloud-serverless + elasticsearch).
• End-to-end: BundleChangelogs_ServerlessProfile_WritesAuthoringRepoNotCatalogRepository uses a catalog with repository: cloud and asserts repo: elasticsearch.
• Docs in cmd-bundle.md, configure-ref.md, changelog.example.yml, and the BundleProfile.Repo comment.

Tests

Related to elastic/elasticsearch#158728, I ran the following command:

docs-builder changelog bundle serverless-release 2026-09-08 "./docs/temp/Elasticsearch serverless Promotion Report.html"

Before this PR, it generated a bundle that contained the following:

products:
- product: cloud-serverless
  target: 2026-09-08
  repo: cloud
  owner: elastic

After this PR, it contains the correct repo name:

products:
- product: cloud-serverless
  target: 2026-09-08
  repo: elasticsearch
  owner: elastic

Generative AI disclosure

1. Did you use a generative AI (GenAI) tool to assist in creating this contribution?

• Yes
• No

2. If you answered "Yes" to the previous question, please specify the tool(s) and model(s) used (e.g., Google Gemini, OpenAI ChatGPT-4, etc.).

Tool(s) and model(s) used: Cursor Grok 4.6

[github-actions]

Docs preview (local build)

Handbook preview: https://docs-v3-preview.elastic.dev/elastic/docs-builder/pull/4061/

Sample changed pages:

• docs/cli/changelog/cmd-bundle.md
• docs/data/release-notes/configure-ref.md