Remove unused TODOs from .rubocop_todo.yml

What does this MR do and why?

Those TODOs are superfluous and can be safely removed.

This came up while compiling the list for #354328 (closed).

How to set up and validate locally

bundle exec rubocop --parallel --only Graphql/IDType,Lint/DuplicateRequire,Lint/IdentityComparison,Lint/UnreachableLoop,Naming/MethodParameterName,RSpec/ScatteredSetup,Rails/BulkChangeTable,Style/ConditionalAssignment
...

25289 files inspected, no offenses detected

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.