Update rubocop.govuk

[colinbruce]

What

Update the rubocop govuk gem and then step through each update in turn addressing issues that arose

Three exemptions added to .rubocop.yml:

• FactoryBot/FactoryAssociationWithStrategy, exclude spec/factories/legal_aid_applications.rb
  This is because there are too many traits that create objects that loop back

• RSpec/IndexedLet, set the max number of spec variables to 2

  This will allow up to 2 number let variables e.g.

      let!(:transaction1) { create(:bank_transaction, :benefits, happened_at: 10.days.ago) }
      let!(:transaction2) { create(:bank_transaction, :benefits, happened_at: 40.days.ago) }

  But trying to create transaction3 will raise an error

  The aim is to slowly reduce the number over time to 1 as we phase out the use of large numbered blocks

• Exclude spec/services/cfe/* from RSpec/IndexedLet as the CFE classic integration is due to be deleted soon

Checklist

Before you ask people to review this PR:

• Tests and rubocop should be passing: bundle exec rake
• Github should not be reporting conflicts; you should have recently run git rebase main.
• There should be no unnecessary whitespace changes. These make diffs harder to read and conflicts more likely.
• The PR description should say what you changed and why, with a link to the JIRA story.
• You should have looked at the diff against main and ensured that nothing unexpected is included in your changes.
• You should have checked that the commit messages say why the change was made.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

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13.0% Duplication

[jsugarman]

LGTM 👍 - one comment re: contrary cops MatchArray versus ContainExactly. No blockers