MAGETWO-95812: Required RMA Attributes are not validated while Customer submits a return

- Update automated test

Author: VeronikaYarats

app/code/Magento/Sales/Test/Mftf/Metadata/sales_enable_rma_config-meta.xml

@@ -8,7 +8,7 @@
 <operations xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:mftf:DataGenerator/etc/dataOperation.xsd">
     <operation name="SalesRMAConfig" dataType="sales_rma_config" type="create" auth="adminFormKey" url="/admin/system_config/save/section/sales/" method="POST">
         <object key="groups" dataType="sales_rma_config">
-            <object key="magento_rma" dataType="sales_rma_config">
+            <object key="rma" dataType="sales_rma_config">
                 <object key="fields" dataType="sales_rma_config">
                     <object key="enabled" dataType="enabled">
                         <field key="value">string</field>