Use report.VulnerabilityNameMaxLengthBytes

What does this MR do?

This MR removes the vulnerabilityNameMaxLengthBytes constant added by Update golang dependencies (!150 - merged) • Lucas Charles, Thomas Woodham • 16.8 and instead references the new report.VulnerabilityNameMaxLengthBytes constant added by feat: Export vulnerability length constants (report!78 - merged) • Lucas Charles • 16.8.

What are the relevant issue numbers?

N/A

Does this MR meet the acceptance criteria?

• [-] Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
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  • Job definition example
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• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer