CRM-21580 get exportstatusid based on name in stead of value

CRM/Financial/Form/Export.php

@@ -89,8 +89,7 @@ class CRM_Financial_Form_Export extends CRM_Core_Form {
       $this->_batchIds = $this->_id;
     }
 
-    $allBatchStatus = CRM_Core_PseudoConstant::get('CRM_Batch_DAO_Batch', 'status_id');
-    $this->_exportStatusId = CRM_Utils_Array::key('Exported', $allBatchStatus);
+    $this->_exportStatusId = CRM_Core_PseudoConstant::getKey('CRM_Batch_DAO_Batch', 'status_id', 'Exported');
 
     // check if batch status is valid, do not allow exported batches to export again
     $batchStatus = CRM_Batch_BAO_Batch::getBatchStatuses($this->_batchIds);