Fix auto scroll to secure form issue

[aashishgurung]

1. Objective

Fix auto scroll to secure form issue

2. Description of change

• Added a check on existence of the secure form on updated_checkout event. This event was triggering when we update postal code.
• Hidden the secure form when iframe is loaded to avoid auto scroll to the iframe. We make is visible again after 1 sec.

3. Quality assurance

Precondition:

• Use mobile device
• Enable secure form from WP admin
• There should not be any saved card

Case 1:

• Add items to cart and checkout
• Fill in the billing info.
• When you update postal code, the focus should not be shifted to credit card form.

Case 2:

• Add items to cart and checkout with credit card. This will set default payment to credit card on your next order
• For the next order, add items to cart and go to checkout page. The page should not scroll down to the credit card form.

🔧 Environments:

• WooCommerce: v8.3.1
• WordPress: v6.4.2
• PHP version: 8.1

4. Impact of the change

• N/A

5. Priority of change

Normal

6. Additional Notes

• N/A

[aashishgurung]

Closing this PR as the issue can be resolved by making changes in the dependent JS pacakge.