[WS-2315] High Impact Promo to use relatedTopic instead of attribution

[LukasFrm]

Resolves JIRA: https://bbc.atlassian.net/browse/WS-2315

Summary

A follow up to #13570 after discussing its caveats with the article team (change affect PS pages).

This change fixes how related topic data is passed down from BFF. When received, this new relatedTopic property is then conditionally rendered in MAXIMUM visual prominence HIP components in Simorgh instead of a regular article attribution.

Code changes

• List key code changes that have been made.

Testing

1. Open https://www.test.bbc.com/ws/languages
2. First High Impact Promo should display "Россия" instead of "Russian" as the former is a related topic of the article.

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[Copilot]

Pull request overview

Updates the High Impact Promo curation component to display a relatedTopic link (when provided) in place of the usual attribution, aligning promo rendering with updated backend payload expectations.

Changes:

• Add optional relatedTopic prop to HighImpactPromo and prefer it over attributions when rendering the subject link.
• Refactor subject-link selection logic to fall back to first attribution or brand link/text when relatedTopic is absent.
• Extend unit tests to cover rendering and prioritisation of relatedTopic.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/app/components/Curation/HighImpactPromo/index.tsx	Adds relatedTopic support and prioritised rendering logic over attributions.
src/app/components/Curation/HighImpactPromo/index.test.tsx	Adds test coverage for relatedTopic rendering and precedence over attributions.

[elvinasv]

Ask talked offline, given that we're introduced relatedTopic which contains the primary topic of the article, should we remove the attributions for HighImpactPromo?

There may be unintended consequences if topics are missing but attributions are still returned, especially since Editorial might not have an easy way to control this.