[C++][Parquet] Parquet: buffered column writer uses unbuffered page writer

### Describe the bug, including details regarding any error messages, version, and platform.

https://github.com/apache/arrow/pull/35886/files#r1271424177

In `RowGroupSerializer::InitColumns`, the `buffered` flag is ignored after https://github.com/apache/arrow/pull/35886. Causing Buffered RowGroup Writer uses unbuffered page writer.

### Component(s)

C++, Parquet