Fix all of the rubocop warnings that we can automatically

What does this MR do and why?

Fix all of the rubocop warnings we could fix by using rubocop -a and rubocop -A.

• The .rubocop_todo.yml is much smaller 🎉
• This MR also fixes a deprecation warning from activesupport

Expected impact & dry-runs

None, since the specs are green and that the rubocop job is also green 💚

Action items

• (If applicable) Add documentation to the handbook pages for Triage Operations =>
• (If applicable) Identify the affected groups and how to communicate to them:
  • /cc @person_or_group =>
  • Relevant Slack channels =>
  • Engineering week-in-review