Preserve multiline semantics on Rails/Presence

[ydah]

Similar issue: rubocop/rubocop#10784

Before

if a.present?
+^^^^^^^^^^^^^ Use `a.presence || b.to_f * 12.0` instead of `if a.present?
+  a
+else
+  b
+end`.
  a
else
  b
end

After

if a.present?
+^^^^^^^^^^^^^ Use `a.presence || b` instead of `if a.present? ... end`.
  a
else
  b
end

---

Before submitting the PR make sure the following are checked:

• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Wrote good commit messages.
• [-] Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Ran bundle exec rake default. It executes all tests and runs RuboCop on its own code.
• Added an entry (file) to the changelog folder named {change_type}_{change_description}.md if the new code introduces user-observable changes. See changelog entry format for details.
• [-] If this is a new cop, consider making a corresponding update to the Rails Style Guide.

[koic]

Thanks!