fix: change to use mwc token for tenant setting check (#2300)

Co-authored-by: cruise <cruiseli@microsoft.com>

core/src/main/scala/com/microsoft/azure/synapse/ml/fabric/OpenAIFabricSetting.scala

@@ -9,7 +9,7 @@ trait OpenAIFabricSetting extends RESTUtils {
 
   private def getHeaders: Map[String, String] = {
     Map(
-      "Authorization" -> s"Bearer ${TokenLibrary.getAccessToken}",
+      "Authorization" -> FabricClient.getCognitiveMWCTokenAuthHeader,
       "Content-Type" -> "application/json"
     )
   }