WS-2501 - Prepare topic discovery for rollout

[LilyL0u]

This pull request enhances the TopicDiscovery component with improved support for right-to-left (RTL) languages, adds arabic story to storybook so it can be tested. It introduces new test fixtures and Storybook stories for Arabic topics, ensures correct RTL rendering, and removes unused experiment-related code for both click and view tracking. The changes also include minor styling and prop cleanup.

RTL and Arabic Support Enhancements:

• Added Arabic topic fixtures and multiple-topic data to fixtures.ts, enabling comprehensive testing and story coverage for RTL languages.
• Updated Storybook stories (index.stories.tsx) to include scenarios for Arabic topics and RTL rendering, using new fixtures and a fetch mock decorator.
• Expanded tests in index.test.tsx to verify correct RTL rendering, topic switching, and text direction for Arabic topics. [1] [2]

Component and Prop Simplification:

• Removed unused experimentProps from TopicDiscovery and related components, cleaning up the props and internal logic. [1] [2] [3] [4] [5] [6]
• Ensured the dir attribute is set on the main section element based on the current service's direction (LTR or RTL), improving accessibility and layout for RTL languages.

Event Tracking Cleanup:

• Removed all topic discovery–related experiment tracking logic from both click (useClickTrackerHandler) and view (useViewTracker) hooks, as these experiments are no longer active. [1] [2] [3] [4]

Styling Adjustments:

• Simplified the moreAboutLink style by removing unnecessary padding, making the styling more consistent.

Miscellaneous:

• Cleaned up unused imports and props in ArticlePage.tsx, including the removal of experiment-related context and props. [1] [2] [3]
• Resolves JIRA: https://bbc.atlassian.net/browse/WS-2501

Also adds the topic discovery component to the media article page with the same toggle and same conditional logic.

I sent @eagerterrier a file to upload to enable the toggles on test, as the interface is currently not working properly.

Some screenshots:

Summary

A very high-level summary of easily-reproducible changes that can be understood by non-devs, and why these changes where made.

Code changes

• List key code changes that have been made.

Testing

1. List the steps required to test this PR.

Useful Links

• Coding Standards
• Repository use guidelines
• Add Links to useful resources related to this PR if applicable.