Prioritize post description over title for Linkedin's share previews

[bernattorras]

Part of Automattic/wp-calypso#105796

Proposed changes:

• Prioritize post description over title for Linkedin's share previews

Other information:

Currently, the LinkedIn post preview prioritizes the post title over the body. As per Automattic/wp-calypso#105796, we're trying to improve the Linkedin share functionality to include part of its content (if no custom social message or excerpt is found) instead of the title.

With this change, it will now be possible to access the post description in the LinkedInPostPreview component from calypso's @automattic/social-previews.

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
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Testing instructions:

Once merged, we should follow the testing instructions detailed in Automattic/wp-calypso#105796

Does this pull request change what data or activity we track or use?

No. It just changes the data (description instead of the title) that is sent to the LinkedIn's share post preview.

[github-actions]

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[github-actions]

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Code Coverage Summary

This PR did not change code coverage!

That could be good or bad, depending on the situation. Everything covered before, and still is? Great! Nothing was covered before? Not so great. 🤷

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