Fixes#9485.

This PR fixes a warning that can be issued when downloading results as pyarrow record batches.

The warning was caused bypyarrow, because apyarrow schema was passed as thenames argument, instead of as theschema argument, andpyarrow started raising a warning for it in version0.15.0 (source code).

Steps to reproduce

• Make surepyarrow 0.15.0+ is installed (there is no warning in prior versions),
• Runquery_to_arrow test,

Actual result (before the fix):
Apyarrow FutureWarning is issued (as described in the issue description).

Expected result (after the fix):
No warning is issued, everything works as expected.