Topic is temporarily unavailable

**Describe the bug**
When the leader node tries to unload the topic and times out, the node where the topic is located will display Topic is temporarily unavailable。
version:2.8.1
topic type:persistent

**To Reproduce**
Steps to reproduce the behavior:
1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

**Expected behavior**
A clear and concise description of what you expected to happen.

**Screenshots**
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**Desktop (please complete the following information):**
- OS: [e.g. iOS]

**Additional context**
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Start by reproducing the reported persistent-topic case in Apache Pulsar 2.8.1, focusing on a leader-node unload timeout and the resulting message on the node hosting the topic. The issue provides screenshots but no source file, test, complete reproduction steps, or expected behavior; done should include a confirmed cause and a regression-tested correction.

Written by the indexing model from the issue text.