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MINOR: [C++][Parquet] Change static_pointer_cast to static_cast for DataPage (#41304)



### Rationale for this change

`cpp/src/parquet/column_reader.cc` uses `static_pointer_cast` to cast `current_page_` to specific page. This may introduce unneccessary counting

### What changes are included in this PR?

Change `static_pointer_cast` to `static_cast`.

### Are these changes tested?

No need

### Are there any user-facing changes?

no

Authored-by: mwish <maplewish117@gmail.com>
Signed-off-by: Gang Wu <ustcwg@gmail.com>