[TEST] SessionsResourceSuite: - open/close and count session *** FAILED ***

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)

### Search before asking

- [X] I have searched in the [issues](https://github.com/apache/kyuubi/issues?q=is%3Aissue) and found no similar issues.

### What kind of test improve?

- [X] Fix flaky tests.
- [ ] Fix bug in tests.
- [ ] Increase test coverage.
- [ ] Other kinds of test improve.

### Describe the issues of the existing tests or improvements for new tests

https://github.com/apache/kyuubi/actions/runs/6438768905/job/17485664973?pr=5336

```
SessionsResourceSuite:
- open/close and count session *** FAILED ***
1 equaled 1, but 0 did not equal 1 (SessionsResourceSuite.scala:65)
- getSessionList *** FAILED ***
List(Map("duration" -> 0, "sessionType" -> "INTERACTIVE", "identifier" -> "bfe26bd7-9010-40f8-beed-3b125f3be756", "createTime" -> 1696651764791, "ipAddr" -> "127.0.0.1", "exception" -> "", "kyuubiInstance" -> "localhost:38463", "idleTime" -> 61, "engineId" -> "", "conf" -> Map("kyuubi.session.real.user" -> "anonymous", "testConfig" -> "testValue", "kyuubi.client.ipAddress" -> "127.0.0.1", "kyuubi.session.connection.url" -> "localhost:38463", "kyuubi.server.ipAddress" -> "localhost"), "user" -> "anonymous")) was not empty (SessionsResourceSuite.scala:104)
```

### Are you willing to submit PR?

- [ ] Yes. I would be willing to submit a PR with guidance from the Kyuubi community to improve.
- [ ] No. I cannot submit a PR at this time.

Start with SessionsResourceSuite.scala, especially the failing assertions at lines 65 and 104, and reproduce the failures from the linked GitHub Actions run. Determine why the open/close count and session-list assertions are flaky, then make the suite pass reliably with the expected count and an empty list.

Written by the indexing model from the issue text.