Instead of maintaining two templates, there should be a
single source of truth.

Reverts https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/26520
for Security/DAST.gitlab-ci.yml.

Container Scanning, Dependency Scanning, License Management
and SAST parts of Auto DevOps now use the preexisting templates.

Auto DevOps and the DAST job template will now use a
shared job template instead of maintaining two copies
of the job. This also allows Auto DevOps to use custom
authentication with DAST.

Update Dependency Scanning and add other templates