fix comment

Signed-off-by: peiyu <125331682@qq.com>

Author: sd4324530

fluss-server/src/test/java/org/apache/fluss/server/DynamicConfigChangeTest.java

@@ -98,7 +98,7 @@ void testAlterLakehouseConfigs() throws Exception {
                                                             AlterConfigOpType.SET))))
                     .isExactlyInstanceOf(ConfigException.class)
                     .hasMessageContaining(
-                            "The config key un_support_key is not allowed to be changed dynamically.");
+                            "The config key un_support_key is not allowed to be changed dynamically or invalid (non-existent).");
 
             dynamicConfigManager.alterConfigs(
                     Arrays.asList(