Restore required expectation

It is the whole purpose of the spec.

spec/lib/reports/bulk_coop_report_spec.rb

@@ -186,6 +186,7 @@ module Reporting
           let!(:line_item) { create(:line_item, order: order) }
 
           it 'calls #new_outstanding_balance' do
+            expect_any_instance_of(Spree::Order).to receive(:new_outstanding_balance)
             CustomerPayments.new(user).__send__(:customer_payments_amount_owed, [line_item])
           end
         end