MAGETWO-98703: CSV file is not exported

- Fix functional test

Author: VeronikaYarats

dev/tests/functional/tests/app/Magento/ImportExport/Test/Constraint/AssertExportSubmittedMessage.php

@@ -16,7 +16,8 @@ class AssertExportSubmittedMessage extends AbstractConstraint
     /**
      * Text value to be checked.
      */
-    const MESSAGE = 'Message is added to queue, wait to get your file soon';
+    const MESSAGE = 'Message is added to queue, wait to get your file soon.'
+        . ' Make sure your cron job is running to export the file';
 
     /**
      * Assert that export submitted message is visible after exporting.