Fix Container Scanning job with K8S runners

changelogs/unreleased/11448-fix-cs-with-k8s-runners.yml

+---
+title: Fix Container Scanning job timeout when using the kubernetes executor
+merge_request: 29706
+author: 
+type: fixed

lib/gitlab/ci/templates/Security/Container-Scanning.gitlab-ci.yml

@@ -30,7 +30,7 @@ container_scanning:
   services:
     - docker:stable-dind
   script:
-    - if [ -z "$DOCKER_HOST" -a "$KUBERNETES_PORT" ]; then { export DOCKER_SERVICE="localhost" ; export DOCKER_HOST="tcp://${DOCKER_SERVICE}:2375" ; } fi
+    - if [[ -n "$KUBERNETES_PORT" ]]; then { export DOCKER_SERVICE="localhost" ; export DOCKER_HOST="tcp://${DOCKER_SERVICE}:2375" ; } fi
     - |
       if [[ -n "$CI_REGISTRY_USER" ]]; then
         echo "Logging to GitLab Container Registry with CI credentials..."