Remove references to qa-sast

What does this MR do?

Remove references to qa-sast because SAST no longer uses downstream QA tests as of Disable SAST and SD downstream QA tests (gitlab-org/security-products/ci-templates!356 - merged) • James Liu • 16.1, and we're now encountering failing pipelines because qa-sast.yml has been completely removed in Fix verify_templates script (gitlab-org/security-products/ci-templates!474 - merged) • Adam Cohen • 18.4.

What are the relevant issue numbers?

• Remove all SAST QA projects and references (gitlab-org/gitlab#567203 - closed) • Adam Cohen • 18.4
• Improve SAST analyzer tests (gitlab-org/gitlab#366852 - closed) • rossfuhrman, Lucas Charles+ • 15.9 • Needs attention
• Secure Test Projects - Remove SAST / SAST QA (gitlab-org/gitlab#462109 - closed) • Will Meek