Add support for partial scans

What does this MR do?

Add support to configure a report to be a partial scan based on the new field introduced in Add support for partial scan mode (gitlab-org/security-products/security-report-schemas!171 - merged)

What are the relevant issue numbers?

gitlab-org/gitlab#540584 (closed)

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
• Ensure the report version matches the equivalent schema version
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer