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MINOR: [R] Clean up a linting issue from #45261 (#45575)

### Rationale for this change

Cleanup a minor formatting issue introduced in #45261

### What changes are included in this PR?

Remove two new lines

### Are these changes tested?

Yes operative changes, linter should pass

### Are there any user-facing changes?

No

Authored-by: Jonathan Keane <jkeane@gmail.com>
Signed-off-by: Antoine Pitrou <antoine@python.org>