fix: small tweaks for Lazy Load tab

[Soare-Robert-Daniel]

All Submissions:

• Have you followed the Optimole Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Based on https://github.com/Codeinwp/optimole-service/issues/1559#issuecomment-3362609201

• Add the requested tweaks to the UI for the Lazy Load page
• When both Skip the images and Skip above the Fold are unchecked, use the old all value.

Closes https://github.com/Codeinwp/optimole-service/issues/1559#issuecomment-3362609201

How to test the changes in this Pull Request:

1. Check the UI
2. Check the saving value of Skip first image and Above the fold when they are both unchecked.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?

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🎉 This PR is included in version 4.1.0 🎉

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