GH-49506: [CI][Python] Doctest fails when pyarrow._cuda absent

[rok]

Rationale for this change

See #49506.

What changes are included in this PR?

We skip cuda docstests in CI, since we don't build for CUDA.

Are these changes tested?

We currently see failing CI. That should go away.

Are there any user-facing changes?

Only to CI users.

• GitHub Issue: [CI][Python] Doctest fails when pyarrow._cuda absent #49506

[github-actions]

⚠️ GitHub issue #49506 has been automatically assigned in GitHub to PR creator.

[rok]

Crossposting from the issue:

This is likely due to the new release of pytest-cython v0.4.0 that started to be used on runners.

--doctest-cython now collects .pyx files even when binary doesn't exist (see v0.3.0 vs v0.4.0)

[rok]

@raulcd - this is to fix the current CI failure. Quick check before I merge?

[raulcd]

LGTM minor nit, feel free to ignore

[rok]

Thanks for review @raulcd, will merge once CI is green.

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 3 benchmarking runs that have been run so far on merge-commit a315b96.

There were no benchmark performance regressions. 🎉

The full Conbench report has more details. It also includes information about 17 possible false positives for unstable benchmarks that are known to sometimes produce them.