Drop ruleset package

What does this MR do?

Drops ruleset package in favor of https://gitlab.com/gitlab-org/security-products/analyzers/ruleset now that all SAST analyzers have been updated to rely on it

What are the relevant issue numbers?

• Relates to gitlab-org/gitlab#211819 (closed)
• Fixes gitlab-org/gitlab#296770 (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
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer