Flaky test: org.keycloak.testsuite.adapter.servlet.OfflineServletsAdapterTest#testServlet

## org.keycloak.testsuite.adapter.servlet.OfflineServletsAdapterTest#testServlet
[Keycloak CI - Base IT (2)](https://github.com/keycloak/keycloak/actions/runs/5501686403/jobs/10025549683)

```
java.lang.AssertionError: 

Expected: not null
     but: was null
	at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:20)
...
```
