Use default chunk size as 4 MB than than 16Mb in arrow's rolling policy

### Describe the enhancement requested

Apache Arrow currently calculates chunk sizes based on the assumption that Netty's PooledByteBufAllocatorL uses a 16MB page size. If size is blow 16MB, will use nextPowerOfTwo of requestSize.

```java
public long getRoundedSize(long requestSize) {
return requestSize < chunkSize ? CommonUtil.nextPowerOfTwo(requestSize) : requestSize;
}
```
However, Netty's default maximum buffer size has been reduced from 16MB to 4MB in recent versions (see https://github.com/netty/netty/pull/12108). This mismatch leads to memory inefficiency in scenarios where chunk sizes fall between 4MB and 16MB.

先找出包含 getRoundedSize 和 chunkSize 預設值的 rolling policy 實作，然後閱讀 CommonUtil.nextPowerOfTwo 的使用方式。將該 policy 與 issue 中描述的 Netty 4 MB 預設值進行比較。當預設值使用 4 MB，且相關測試（如果有）涵蓋 request 大小的現有行為時，即表示完成。

由索引模型根據 Issue 內容生成。