Fix a 'Style/RegexpLiteralMixedPreserve' RuboCop offense

What does this MR do?

Fix a 'Style/RegexpLiteralMixedPreserve' RuboCop offense (#327715 (closed))

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • [-] I have included a changelog entry.
  • [-] I have not included a changelog entry because _____.
• [-] Documentation (if required)
• Code review guidelines
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• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

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• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done