Fix Link payment issues

[Mayisha]

Fixes #2958

Changes proposed in this Pull Request:

Link payment is failing in 2 places. In the block cart page and shortcode checkout page. We added some required field checks for the PRBs in #2886 which is causing the issue.

• In block cart page, it was looking for the checkout fields. Added a early return there.
• In shortcode checkout page, Jquery was picking up some fields from the Link pop-up. Added check for name and value field there to avoid the Link fields.

Testing instructions

• Go to Stripe settings page and enable UPE.
• Enabled Link.
• As a shopper purchase a product from all of the following pages
• Product
• Shortcode cart
• Shortcode checkout
• Block cart
• Block checkout
• Purchases with Link from all the above pages should be successful without any error.

Additional testing

Test the steps from #2886 to make sure the required field issue did not resurface with the changes in this PR.

[a-danae]

Thanks for the quick fix for this, @Mayisha !

Looks good to me but not approving yet as I'd like to take another look at the validation. Partial review for now.

Payment processing works fine in:

• Product
• Shortcode cart
• Shortcode checkout
• Block cart
• Block checkout

I tested the field validation continue to work as expected and that seems okay. There's a behavior that's strange, but we're already having that in trunk and it's not critical. I'll open a separate issue for it.

[a-danae]

Looks good to me! 👍

Validation continues to work both checkouts.

There's another unexpected behavior where the payment isn't processed in the block checkout when the company field isn't filled, but there's no company field. I can replicate this in trunk as well, so it wasn't introduced in this PR. All good with addressing it separately.

[Mayisha]

There's another unexpected behavior where the payment isn't processed in the block checkout when the company field isn't filled, but there's no company field.

I will check what might be causing the issue.

[a-danae]

I will check what might be causing the issue.

Thanks! It already exists in trunk, so we can probably create a task for this and triage it along with the other issues.