Flaky-test: KeySharedSubscriptionTest

### Search before reporting

- [x] I searched in the [issues](https://github.com/apache/pulsar/issues) and found nothing similar.

### Example failure

https://github.com/apache/pulsar/actions/runs/34130276934/job/101987362625

### Exception stacktrace

```text
Attempt 2:

Gradle suite > Gradle test > org.apache.pulsar.client.api.KeySharedSubscriptionTest > resetDefaultNamespace FAILED
org.apache.pulsar.client.admin.PulsarAdminException$PreconditionFailedException: Topic has 8005 clients connected Including 8004 consumers, 0 producers, and 0 replicators.
at app//org.apache.pulsar.client.admin.PulsarAdminException.wrap(PulsarAdminException.java:252)
at app//org.apache.pulsar.client.admin.internal.BaseResource.sync(BaseResource.java:480)
at app//org.apache.pulsar.client.admin.internal.TopicsImpl.delete(TopicsImpl.java:510)
at app//org.apache.pulsar.client.admin.Topics.delete(Topics.java:894)
at app//org.apache.pulsar.client.api.KeySharedSubscriptionTest.resetDefaultNamespace(KeySharedSubscriptionTest.java:188)

Caused by:
jakarta.ws.rs.ClientErrorException: HTTP 412 {"reason":"Topic has 8005 clients connected Including 8004 consumers, 0 producers, and 0 replicators."}
at app//org.glassfish.jersey.client.JerseyInvocation.createExceptionForFamily(JerseyInvocation.java:1002)
at app//org.glassfish.jersey.client.JerseyInvocation.convertToException(JerseyInvocation.java:984)
at app//org.glassfish.jersey.client.JerseyInvocation$1.completed(JerseyInvocation.java:879)
at app//org.glassfish.jersey.client.ClientRuntime.processResponse(ClientRuntime.java:232)
at app//org.glassfish.jersey.client.ClientRuntime$2.lambda$response$0(ClientRuntime.java:176)
at app//org.glassfish.jersey.internal.Errors$1.call(Errors.java:248)
at app//org.glassfish.jersey.internal.Errors$1.call(Errors.java:244)
at app//org.glassfish.jersey.internal.Errors.process(Errors.java:292)
at app//org.glassfish.jersey.internal.Errors.process(Errors.java:274)
at app//org.glassfish.jersey.internal.Errors.process(Errors.java:244)
```

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

Start with KeySharedSubscriptionTest.java, especially resetDefaultNamespace at line 188, and run the failing test to reproduce the cleanup failure. Trace why consumers remain connected when the topic is deleted; done means the test reliably completes without the connected-client precondition failure.

Written by the indexing model from the issue text.