GH-48386: [Ruby][Dev] Enable Layout/TrailingEmptyLines: final_newline cop

[hiroyuki-sato]

Rationale for this change

This fix introduces new Ruby formatting checks to streamline multi-person development.

What changes are included in this PR?

Enable Layout/TrailingEmptyLines options

# `final_newline` looks for one newline at the end of files.

# bad
class Foo; end

# EOF

# bad
class Foo; end # EOF

# good
class Foo; end
# EOF

Are these changes tested?

Yes.

Are there any user-facing changes?

No.

• GitHub Issue: [Ruby][Dev] Enable Layout/TrailingEmptyLines: final_newline cop #48386

[github-actions]

⚠️ GitHub issue #48386 has been automatically assigned in GitHub to PR creator.

[kou]

+1

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 3 benchmarking runs that have been run so far on merge-commit ba27b8f.

There were no benchmark performance regressions. 🎉

The full Conbench report has more details. It also includes information about 2 possible false positives for unstable benchmarks that are known to sometimes produce them.