Removes two unnecessary cells + adds missing unit test for an existing cell

ios/chrome/browser/payments/cells/order_summary_total_item.h

Index: ios/chrome/browser/payments/cells/order_summary_total_item.h
diff --git a/ios/chrome/browser/payments/cells/order_summary_total_item.h b/ios/chrome/browser/payments/cells/order_summary_total_item.h
deleted file mode 100644
index 07ba156624f5f2fd16acb5b7f6ab176af4911233..0000000000000000000000000000000000000000
--- a/ios/chrome/browser/payments/cells/order_summary_total_item.h
+++ /dev/null
@@ -1,18 +0,0 @@
-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef IOS_CHROME_BROWSER_PAYMENTS_CELLS_ORDER_SUMMARY_TOTAL_ITEM_H_
-#define IOS_CHROME_BROWSER_PAYMENTS_CELLS_ORDER_SUMMARY_TOTAL_ITEM_H_
-
-#import <UIKit/UIKit.h>
-
-#import "ios/chrome/browser/ui/collection_view/cells/collection_view_detail_item.h"
-
-// OrderSummaryTotalItem is the model class for a CollectionViewDetailItem with
-// custom font properties.
-@interface OrderSummaryTotalItem : CollectionViewDetailItem
-
-@end
-
-#endif  // IOS_CHROME_BROWSER_PAYMENTS_CELLS_ORDER_SUMMARY_TOTAL_ITEM_H_