Add refresh_expiry parameter to additionalParameters

Fix IAS request parameters
this mentioned request parameter is unknonw in IAS, but we know refresh_expiry from https://jira.tools.sap/browse/SECREQ-5220

Author: strehle

cloudplatform/connectivity-oauth/src/main/java/com/sap/cloud/sdk/cloudplatform/connectivity/OAuth2Service.java

@@ -230,7 +230,7 @@ private void setAppTidInCaseOfIAS( @Nullable final String tenantId )
             additionalParameters.put("app_tid", tenantId);
             if( onBehalfOf == OnBehalfOf.NAMED_USER_CURRENT_TENANT ) {
                 // workaround until a fix is provided by IAS
-                additionalParameters.put("refresh_token", "0");
+                additionalParameters.put("refresh_expiry", "0");
             }
         }
     }