[Bug] getPartitionsForTopic Cause Signal 11 SIGSEGV （Segmentation Fault）

### Search before asking

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

### Version

CPP Client： 3.6.0
pulsar broker： 3.0.4

### Minimal reproduce step

1、create pulsar client
2、invoke client getPartitionsForTopic to get partition

### What did you expect to see?

can get partition correctlly

### What did you see instead?

Signal ID:11 Pid:920
Time:1731978465
/opt/lib/libpulsar.so(_ZN6pulsar6Client26getPartitionsForTopicAsyncERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt8functionIFvNS_6ResultERKSt6vectorIS6_SaIS6_EEEE+0x10)[0xffff17ac16d8]
/opt/lib/libpulsar.so(_ZN6pulsar6Client21getPartitionsForTopicERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEERSt6vectorIS6_SaIS6_EE+0xd8)[0xffff17ac5df0]

### Anything else?

This issue does not occur every time; it happens only with a certain probability.

### Are you willing to submit a PR?

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

首先，使用 C++ 客户端 3.6.0 和 broker 3.0.4 重现报告的间歇性崩溃，以 Client::getPartitionsForTopic 和 getPartitionsForTopicAsync 作为入口点。检查 stack trace 所示位置的故障，并比较针对不同 topic 的重复调用。完成标准是分区查找能够始终返回正确结果且不发生 SIGSEGV。

由索引模型根据 Issue 内容生成。