Add unit tests for security orchestration schema

What does this MR do and why?

This MR:

• adds unit tests for our security orchestration JSON schema
• fixes key pattern validation for scan result policy variables by specifying additionalProperties: false (related explanation)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #396272 (closed)