Add integration test Spec

What does this MR do?

To bring this project inline with the other analyzers, this MR adds an RSpec integration test to ensure the scanner is working as expected.

What are the relevant issue numbers?

This MR relates to but is not required by gitlab-org/gitlab#373921 (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 updated/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