Automatically fixed EmptyLineAfterFinalLet in model and controller specs

What does this MR do?

#34182 (closed)

Ran: bundle exec rubocop --only RSpec/EmptyLineAfterFinalLet -a spec/models/ spec/controllers/

Originally covered by !18853 (closed) but split so that merge conflicts are less of an issue.

Once this and !21873 (merged) are merged I can raise an MR to pick up any stragglers and remove the rubocop todo.

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Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

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• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
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