Release testing instructions for WC Payments 8.7.0

Add seller_message to failed order notes

PR #9934

• Use card 4000 0000 0000 0002 for testing.
• In the checkout, as a shopper, you will still see the generic decline Your card was declined.
• However, as a merchant, in the order note, you can see more details like this:

Transaction Fee shows when payment is authorized but not captured

[PR #9997] (https://github.com/Automattic/woocommerce-payments/pull/9997)

1. Set WooPayments to "Issue an authorization on checkout, and capture later."

2. Switch to the develop branch or use the plugin version without this change.

3. Add an item to the cart and process the payment on the checkout page.

4. Go to the order's view screen in the WP Admin page and confirm that the transaction fee is displayed as shown below:
   

5. Switch to this branch.

6. Repeat the steps above.

7. On the order's view screen in WP Admin, notice that the transaction fee is no longer displayed since the transaction is not yet captured.

8. Capture the transaction in the Transactions tab.
9. Return to the order's view screen in WP Admin.
10. Confirm that the transaction fee is now displayed.