Fix golangci-lint prealloc lint errors

What does this MR do?

This MR addresses all findings reported by the prealloc linter that is to be activated in the default golangci-lint config. See Activate `prealloc` linter (gitlab-org/security-products/ci-templates!322 - merged) for more information.

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
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer