MAGETWO-98703: CSV file is not exported

- Added validation message to 'exportAllProducts' actionGroup

Author: Lusine-Papyan

app/code/Magento/CatalogImportExport/Test/Mftf/ActionGroup/AdminExportActionGroup.xml

@@ -34,7 +34,7 @@
         <wait stepKey="waitForScroll" time="5"/>
         <click selector="{{AdminExportAttributeSection.continueBtn}}" stepKey="clickContinueButton"/>
         <wait stepKey="waitForClick" time="5"/>
-        <see selector="{{AdminMessagesSection.successMessage}}" userInput="Message is added to queue, wait to get your file soon" stepKey="seeSuccessMessage"/>
+        <see selector="{{AdminMessagesSection.successMessage}}" userInput="Message is added to queue, wait to get your file soon. Make sure your cron job is running to export the file" stepKey="seeSuccessMessage"/>
     </actionGroup>
 
     <!-- Download first file in the grid -->