MINOR: [C++] Make argument name consistent

[pitrou]

Followup to #44955

[github-actions]

❌ GitHub issue #undefined could not be retrieved.

[github-actions]

❌ GitHub issue #undefined could not be retrieved.

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❌ GitHub issue #undefined could not be retrieved.

[pitrou]

@kou @raulcd The "Dev PR" failure is weird here, any idea?

[github-actions]

❌ GitHub issue #undefined could not be retrieved.

[raulcd]

The "Dev PR" failure is weird here, any idea?

I think I broke the check for PRs with MINOR when removing the JIRA code. We were checking whether it was a JIRA issue or a GitHub issue in the past (or doing nothing if it wasn't either). Now we assume is a GitHub issue:
https://github.com/apache/arrow/pull/44936/files#diff-cdf16bb28f8aef5eeb1213fa302a992b3c8f8eba0e2b7af893e794cb5cdbf0fcR80-R83

I'll open an issue to fix this.

[raulcd]

I've opened: #44974

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 3 benchmarking runs that have been run so far on merge-commit e747af6.

There were no benchmark performance regressions. 🎉

The full Conbench report has more details. It also includes information about 78 possible false positives for unstable benchmarks that are known to sometimes produce them.