[Admin] Emptying the cart doesn't update the cart/order totals

[spaghetticode]

Solidus Version: all, including master

To Reproduce Please check the attached video: https://www.loom.com/share/ad878419beab485c84deb35c13a3413d

Add an item to the cart, and then push the Empty Cart button. All items will be removed from the cart, but given the request is remote the totals shown on the page are not being updated. This is a very minor issue, but I think it's still worth reporting.

Current behavior Order totals on the page are not updated (should be set to zero).

Expected behavior Order totals on the page are updated to zero.