MC-4543: Convert MassAssignCustomerGroupTest to MFTF

- Making action group clearer

Author: aljcalandra

app/code/Magento/Customer/Test/Mftf/ActionGroup/SetGroupCustomerActionGroup.xml

@@ -8,7 +8,7 @@
 
 <actionGroups xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
               xsi:noNamespaceSchemaLocation="urn:magento:mftf:Test/etc/actionGroupSchema.xsd">
-    <actionGroup name="SetCustomerGroupForSelectedCustomer">
+    <actionGroup name="SetCustomerGroupForSelectedCustomersViaGrid">
         <arguments>
             <argument name="groupName" type="string"/>
         </arguments>

app/code/Magento/Customer/Test/Mftf/Test/ChangeCustomerGroupTest.xml

@@ -41,7 +41,7 @@
         <actionGroup ref="AdminSelectCustomerByEmail" stepKey="selectCustomer">
             <argument name="customerEmail" value="$createCustomer.email$"/>
         </actionGroup>
-        <actionGroup ref="SetCustomerGroupForSelectedCustomer" stepKey="setCustomerGroup">
+        <actionGroup ref="SetCustomerGroupForSelectedCustomersViaGrid" stepKey="setCustomerGroup">
             <argument name="groupName" value="{{CustomerGroupChange.code}}"/>
         </actionGroup>
         <actionGroup ref="AdminFilterCustomerByName" stepKey="filterCustomerAfterGroupChange">