Fix failing CI pipelines from Security jobs (sast, dependency_scanning)

Fix failing/red CI pipelines from Security jobs (sast, dependency_scanning).

Why did the security Auto DevOps pipelines start failing?

Everything started failing when the DinD support was dropped for sast and dependency_scanning, gitlab-org/gitlab!41260 (merged)

Why are the SAST pipelines not running for every branch/MR?

See gitlab-org/gitlab#238601 (comment 445296597)

See gitlab-org/gitlab#217668 (closed)

Dev notes

Docs: https://docs.gitlab.com/ee/user/application_security/sast/#overriding-sast-jobs

Reference template we are trying to work from:

• https://gitlab.com/gitlab-org/gitlab/-/blob/60e145b1b81ee1061619e4b7a304d51445fef1dd/lib/gitlab/ci/templates/Security/SAST.gitlab-ci.yml