[Backport] Fixed calculation of 'Total' column under "Last Orders" listing on the admin dashboard

[eduard13]

Original Pull Request

#21283

Description (*)

The calculation of 'Total' column under "Last Orders" listing on the admin dashboard was wrong. It has below problems.

1. It wasn't considering the refunded discount amount
2. It was subtracting discount canceled amount instead of adding when viewing data for a particular website or store

Fixed Issues (if relevant)

1. Wrong order amount on dashboard on Last orders listing when order has discount and it is partially refunded #21281: Wrong order amount on the dashboard on Last orders listing when the order has discount and it is partially refunded
2. Negative order amount in dashboard latest order when order is cancelled where coupon has been used #18754: Negative order amount in dashboard latest order when order is cancelled where coupon has been used

Manual testing scenarios (*)

Testing fix for issue##18754

1. Place an order with a coupon code, for example, 4.95 EUR off
2. Cancel the order
3. Go to dashboard select a specific store to view data and notice the total column under "Last Orders" listing

Testing fix for issue##21281

1. Add a product with quantity 3 to Cart
2. Create a 10% discount coupon from admin and apply it to the cart
3. Go to checkout and place order
4. Invoice the order from admin, if placed using the offline payment method
5. Create a credit memo for the order to refund 2 quantities out of 3
6. Now notice the "Total" column for order on the admin dashboard under "Last Orders" listing. The refunded discount amount on credit memo is not considered in the total.

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-engcom-team]

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[dmytro-ch]

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[magento-engcom-team]

Hi @dmytro-ch, thank you for the review.
ENGCOM-4593 has been created to process this Pull Request

[VasylShvorak]

✔️ QA passed

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