Fix product data field description styling, including checkboxes and radio buttons

[mattsherman]

Submission Review Guidelines:

• I have followed the WooCommerce Contributing Guidelines and the WordPress Coding Standards.
• I have checked to ensure there aren't other open Pull Requests for the same update/change.
• I have reviewed my code for security best practices.
• Following the above guidelines will result in quick merges and clear and detailed feedback when appropriate.

Changes proposed in this Pull Request:

This PR tweaks the fix originally supplied in #37791 to improve the product data field description styling, including checkbox and radio buttons. The previous fix, while addressing checkbox and radio buttons, made the styling of descriptions associated with other types of inputs worse on smaller viewports.

This updated implementation keeps the improvement of the checkbox and radio button label styling, and also improves the styling of descriptions associated with other types of inputs by always showing those descriptions below the corresponding input field, regardless of viewport width. This improves situations where the description is long and would wrap oddly before.

I resisted making changes to the structure of the HTML, since that may lead to unexpected issues for extensions. There is certainly a lot of room for improvement, but any such changes would need to be carefully considered.

Before

After

(No visual change to Inventory tab)

How to test the changes in this Pull Request:

1. Go to Products > Add New (/wp-admin/post-new.php?post_type=product)
2. Enable Downloadable
3. Go to the General tab
4. Verify the Schedule link is below the Sale price ($) field
5. Verify the descriptions for Download limit and Download expiry are below the input field
6. Go to the Inventory tab
7. Verify the checkboxes are displayed correctly on both larger and smaller viewports. The checkbox label should always start right next to the checkbox, never fully below it. (This is no change over what was implemented in Fix checkbox label styling on product page tabs #37791)

[github-actions]

Test Results Summary

Commit SHA: e717787

Test 🧪	Passed ✅	Failed 🚨	Broken 🚧	Skipped ⏭️	Unknown ❔	Total 📊	Duration ⏱️
API Tests	267	0	0	2	0	269	0m 50s
E2E Tests	187	0	0	10	0	197	13m 40s

---

To view the full API test report, click here.
To view the full E2E test report, click here.
To view all test reports, visit the WooCommerce Test Reports Dashboard.

[github-actions]

Hi @octaedro,

Apart from reviewing the code changes, please make sure to review the testing instructions as well.

You can follow this guide to find out what good testing instructions should look like:
https://github.com/woocommerce/woocommerce/wiki/Writing-high-quality-testing-instructions

[octaedro]

Good job @mattsherman! LGTM 🚀