Remove before_script from DAST vendored template

lib/gitlab/ci/templates/Security/DAST.gitlab-ci.yml

@@ -21,7 +21,7 @@ dast:
   allow_failure: true
   services:
     - docker:stable-dind
-  before_script:
+  script:
     - export DAST_VERSION=${SP_VERSION:-$(echo "$CI_SERVER_VERSION" | sed 's/^\([0-9]*\)\.\([0-9]*\).*/\1-\2-stable/')}
     - |
       function dast_run() {
@@ -34,7 +34,6 @@ dast:
         /analyze -t $DAST_WEBSITE \
         "$@"
       }
-  script:
     - |
       if [ -n "$DAST_AUTH_URL" ]
       then