[Client] Direct Buffer memory leak on Pulsar Admin API in Java

### Search before asking

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

### Version

pulsar-client-all: 2.10.1
pulsar: 2.10.0
flink-connector-pulsar: 1.17-SNAPSHOT

### Minimal reproduce step

Change the Java from 8 to 11 in flink application which uses `pulsar-client-all`. The console shows that the direct buffer memory leaks in Admin API querying.

### What did you expect to see?

No OOM exception.

### What did you see instead?


### Anything else?

_No response_

### Are you willing to submit a PR?

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

Start with the minimal reproduction described: a Flink application using pulsar-client-all, comparing Java 8 and Java 11 while querying the Pulsar Admin API. Confirm the direct-buffer leak and resulting OOM behavior, then identify the affected Admin API path; done means the reproduction no longer leaks or throws OOM.

Written by the indexing model from the issue text.