arrow

MINOR: [C++][Parquet] Rephrase decimal annotation (#33694)

### What changes are included in this PR?

- Rename the function in the writer properties to `enable_short_decimal_stored_as_integer`.
- Rephrase the comment to explain the behavior in detail.

Authored-by: Gang Wu <ustcwg@gmail.com>
Signed-off-by: Will Jones <willjones127@gmail.com>