ACQE-7412 [MFTF TESTS] AdminCorrectnessInvoicedItemInBundleProductTest

added flat rate as deafult shipping method

Author: chandrakalahanchinal

app/code/Magento/Checkout/Test/Mftf/ActionGroup/GuestCheckoutFillingShippingSectionActionGroup.xml

@@ -16,7 +16,7 @@
             <argument name="customerVar" defaultValue="CustomerEntityOne"/>
             <argument name="customerAddressVar" defaultValue="CustomerAddressSimple"/>
             <!--First available shipping method will be selected if value is not passed for shippingMethod-->
-            <argument name="shippingMethod" defaultValue="" type="string"/>
+            <argument name="shippingMethod" defaultValue="Flat Rate" type="string"/>
         </arguments>
 
         <waitForElementVisible selector="{{CheckoutShippingSection.emailAddress}}" stepKey="waitForEmailField"/>