MQE-1421: Updating EndToEnd Tests

Author: okolesnyk

app/code/Magento/SalesRule/Test/Mftf/ActionGroup/StorefrontSalesRuleActionGroup.xml

@@ -32,8 +32,8 @@
     <!-- Check applied discount in cart summary -->
     <actionGroup name="StorefrontCheckCouponAppliedActionGroup">
         <arguments>
-            <argument name="rule"/>
-            <argument name="discount"/>
+            <argument name="rule" />
+            <argument name="discount" type="string" />
         </arguments>
         <waitForElementVisible selector="{{CheckoutCartSummarySection.discountTotal}}" stepKey="waitForDiscountTotal"/>
         <see userInput="{{rule.store_labels[1][store_label]}}" selector="{{CheckoutCartSummarySection.discountLabel}}" stepKey="assertDiscountLabel"/>