Support repo-prefixed changelog bundle output names

[lcawl]

Relates to elastic/docs-builder#3984

Summary

Profile mode now forwards --repo / --owner. In changelog/bundle-create/action.yml (plan + Docker run) and changelog/bundle-fetch/action.yml (plan), those flags were only on the option-mode branch. They now apply in profile mode too, so a repo: input is used for {repo}-{product}-{version}.yaml (and the matching cdn_url) when bundle.repo is missing.

Docs match the new name. changelog/README.md no longer shows profile output: "{version}.yaml" or “the profile's output pattern.” It describes {repo}-{product}-{version}.yaml, bundle.repo / --repo / git origin, and the legacy {product}-{version}.yaml fallback. The same convention is in the bundle-fetch and bundle-upload READMEs.

Left unchanged: changelog-promotion-bundle.yml — it is profile-only and still relies on bundle.repo or checkout origin. Option-mode examples that pass an explicit output: file are unchanged.

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