Bugfix/fix invalid mappings in queued mode (Azure#428)

* Fix setting temp table mapping only for Txn mode

Author: ag-ramachandran

connector/src/main/scala/com/microsoft/kusto/spark/datasink/KustoWriter.scala

@@ -154,14 +154,13 @@ object KustoWriter {
           stagingTableIngestionProperties.creationTime == null)
       }
 
-      kustoClient.setMappingOnStagingTableIfNeeded(
-        stagingTableIngestionProperties,
-        tableCoordinates.database,
-        tmpTableName,
-        table,
-        crp)
-      if (stagingTableIngestionProperties.flushImmediately) {
-        KDSU.logWarn(className, "It's not recommended to set flushImmediately to true")
+      if (writeOptions.writeMode == WriteMode.Transactional) {
+        kustoClient.setMappingOnStagingTableIfNeeded(
+          stagingTableIngestionProperties,
+          tableCoordinates.database,
+          tmpTableName,
+          table,
+          crp)
       }
 
       if (stagingTableIngestionProperties.flushImmediately) {