update migration guide as well as format change

Author: yutong-27

docs/deployment/migration-guide.md

@@ -21,6 +21,7 @@
 
 * Since Kyuubi 1.12, the support of variable `<KYUUBI_HOME>` substitution in config `kyuubi.metadata.store.jdbc.url` is deprecated, use `{{KYUUBI_HOME}}` instead.
 * Since Kyuubi 1.12, default value of `kyuubi.metrics.json.location` is changed to `{{KYUUBI_HOME}}/metrics`, to restore previous behavior, change it to `{{KYUUBI_WORK_DIR_ROOT}}/metrics`.
+* Since Kyuubi 1.12, session configurations in REST API responses are redacted by default using `kyuubi.server.redaction.regex`. Use `kyuubi.server.conf.retrieveMode` to control this behavior: `REDACTED` (default), `ORIGINAL` (no redaction), or `NONE` (omit configs entirely).
 * Since Kyuubi 1.12, `GET /api/v1/sessions` returns only sessions owned by the authenticated user instead of all sessions on the server. To restore the previous behavior, set `kyuubi.frontend.rest.legacy.v1.sessionsReturnAllUsers=true`.
 * Since Kyuubi 1.12, the configuration `spark.sql.kyuubi.hive.connector.dropTableAsPurgeTable` is introduced by Kyuubi Spark Hive connector(KSHC) to control whether DROP TABLE command completely remove its data by skipping HDFS trash. The default value is false. To restore the legacy behavior, set it to true.
 

kyuubi-server/src/test/scala/org/apache/kyuubi/server/api/v1/SessionsResourceSuite.scala

@@ -462,6 +462,7 @@ class SessionsResourceSuite extends KyuubiFunSuite with RestFrontendTestHelper {
 
   private def withSessionConfDisplayMode(mode: String)(f: => Unit): Unit = {
     conf.set(KyuubiConf.SERVER_CONF_RETRIEVE_MODE, mode)
-    try f finally conf.set(KyuubiConf.SERVER_CONF_RETRIEVE_MODE, "REDACTED")
+    try f
+    finally conf.set(KyuubiConf.SERVER_CONF_RETRIEVE_MODE, "REDACTED")
   }
 }