[Bug] Too high SUnreclaim memery use and does not release memory

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### Search before asking

- [X] I have searched in the [issues](https://github.com/apache/incubator-uniffle/issues?q=is%3Aissue) and found no similar issues.

### Describe the bug

We launch 8 Shuffle Server machine, and there is one machine memory use is very high.
After diagnose, we find there is SUnreclaim too high by run cmd :/etc/meminfo

Event though RSS process is down, the memory is not released.


### Affects Version(s)

0.7.0

### Uniffle Server Log Output

_No response_

### Uniffle Engine Log Output

_No response_

### Uniffle Server Configurations

_No response_

### Uniffle Engine Configurations

_No response_

### Additional context

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

The report concerns SUnreclaim memory growth on one of eight Shuffle Server machines, with RSS falling while memory remains allocated. Start by examining the server's memory use and the reported 0.7.0 context; the issue names no source files, tests, or configuration. Done means identifying and addressing why memory is not released, but the report lacks diagnostic logs and concrete reproduction details.

Written by the indexing model from the issue text.