Revert "Merge branch 'dcouture-custom-appsec-sast-rules' into 'master'"

Reverting !88484 (merged) as it has broken builds for pipelines with docs only changes

https://gitlab.com/gitlab-org/gitlab/-/pipelines/557401471

https://gitlab.com/gitlab-org/gitlab/-/pipelines/557409373

Found errors in your .gitlab-ci.yml: 'ping-appsec-for-sast-findings' job needs 'semgrep-appsec-custom-rules' job, but 'semgrep-appsec-custom-rules' is not in any previous stage You can also test your .gitlab-ci.yml in CI Lint