Docs: Add missing clangsa image to offline SAST analyzer images list

Problem to solve

The section Make GitLab SAST analyzer images available inside your Docker registry is missing the registry.gitlab.com/security-products/clangsa:1 image, which is required by the gitlab-advanced-sast-cpp job for C/C++ analysis in offline environments (SAST.gitlab-ci.yml).

Further details

Users following the offline SAST setup guide will import all listed images but the gitlab-advanced-sast-cpp job will still fail because registry.gitlab.com/security-products/clangsa:1 is not listed in the section. This image is a dependency of the GitLab Advanced SAST C/C++ analyzer.

Proposal

Add registry.gitlab.com/security-products/clangsa:1 to the list of images in the #make-gitlab-sast-analyzer-images-available-inside-your-docker-registry section of doc/user/application_security/sast/_index.md.

The updated list should read:

registry.gitlab.com/security-products/clangsa:1
registry.gitlab.com/security-products/gitlab-advanced-sast:2
registry.gitlab.com/security-products/kubesec:6
registry.gitlab.com/security-products/pmd-apex:6
registry.gitlab.com/security-products/semgrep:6
registry.gitlab.com/security-products/sobelow:6
registry.gitlab.com/security-products/spotbugs:5

Who can address the issue

The author of this issue will work on it

Other links/references