Fix detection of frozen_string_literal comments

What does this MR do?

When refactoring this check in !51263 (diffs) we accidentally swapped the condition.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
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Availability and Testing

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• Tested in all supported browsers
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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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