[FEATURE] add metrics of expired pre-allocated buffer size

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)

### 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 feature

add metrics of expired pre-allocated buffer size

### Motivation

_No response_

### Describe the solution

_No response_

### Additional context

_No response_

### Are you willing to submit PR?

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

The issue names no files, tests, or entry points. Start by searching the repository for existing metrics and the pre-allocated buffer lifecycle, then clarify the metric name, labels, and expiry semantics with maintainers. Done means the expired pre-allocated buffer size is exposed consistently and covered by an appropriate test.

Written by the indexing model from the issue text.