add unit tests to cleanup.R

[awasyn]

Add unit tests to cleanup

• Dependent on : add unit tests to fa2domain #75 (relies on testtthat already added)

• Task: [FEAT] Create Unit tests for functions  #29

• Enhancement (unit tests).

Checklist

• I have read and followed the CONTRIBUTING.md guidelines.
• I have searched for existing content to ensure this is not a duplicate.
• I have performed a self-review of these additions (including spelling, grammar, and related).
• I have added comments to my code to help provide understanding.
• I have added a test which covers the code changes found within this PR.
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@the-mayer

[the-mayer]

Similary to #75, bringing this PR up to date with main and making final adjustments so we can get it ready to merge.

[the-mayer]

Tests inspired a bit of a refactor for condenseRepeatedDomains() that should now handle additional domain separators more gracefully. Thanks!