[KYUUBI #4985] [TEST] Fix loglevel restore behavior of `KyuubiFunSuit…

…e#withLogAppender`

### _Why are the changes needed?_

This method is forked from Apache Spark, and recently, [SPARK-44074](apache/spark#41663) identified and fixed the issue about loglevel restore behavior.

### _How was this patch tested?_
- [ ] Add some test cases that check the changes thoroughly including negative and positive cases if possible

- [ ] Add screenshots for manual tests if appropriate

- [x] [Run test](https://kyuubi.readthedocs.io/en/master/contributing/code/testing.html#running-tests) locally before make a pull request

Closes #4985 from pan3793/test-log.

Closes #4985

4c05bc5 [Cheng Pan] Fix loglevel restore behavior of `KyuubiFunSuite#withLogAppender`

Authored-by: Cheng Pan <chengpan@apache.org>
Signed-off-by: Cheng Pan <chengpan@apache.org>

kyuubi-common/src/test/scala/org/apache/kyuubi/KyuubiFunSuite.scala

@@ -102,6 +102,7 @@ trait KyuubiFunSuite extends AnyFunSuite
           logger.asInstanceOf[Logger].setLevel(restoreLevels(i))
           logger.asInstanceOf[Logger].get().setLevel(restoreLevels(i))
         }
+        LogManager.getContext(false).asInstanceOf[LoggerContext].updateLoggers()
       }
     }
   }