Fix: use container full width when featured image is missing

[Soare-Robert-Daniel]

Summary

Added the case with CSS when the featured image container is missing so the text container can take the full width.

Will affect visual aspect of the product

YES

Screenshots

Before

After

Test instructions

• Select List as the Blog layout
• Create some posts and set featured images for some of them
• Hide the thumbnail for the blog posts
• Check how the posts that have a featured image look

Check before Pull Request is ready:

• I have written a test and included it in this PR
• I have run all tests and they pass
• The code passes when running the PHP CodeSniffer
• Code meets WordPress Coding Standards for PHP, HTML, CSS and JS
• Security and Sanitization requirements have been followed
• I have assigned a reviewer or two to review this PR (if you're not sure who to assign, we can do this step for you)

Closes #4138

[pirate-bot]

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[irinelenache]

@Soare-Robert-Daniel Tested and the issue is fixed now, thank you 🚀

[pirate-bot]

🎉 This PR is included in version 3.7.4 🎉

The release is available on GitHub release

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