arrow

GH-38068: [C++][CI] Fixing Parquet unittest `arrow_reader_writer_test.cc` compile (#38069)



### Rationale for this change

This is introduced in a previous patch. This patch fixed the compile. ( https://github.com/apache/arrow/pull/37854 )

### What changes are included in this PR?

a one-line fixing.

### Are these changes tested?

no

### Are there any user-facing changes?

no

* Closes: #38068

Authored-by: mwish <maplewish117@gmail.com>
Signed-off-by: Joris Van den Bossche <jorisvandenbossche@gmail.com>