Merge branch 'update-helm-chart-version' into 'master'

Update helm chart version used by review-deploy

See merge request gitlab-org/gitlab!26190

.gitlab/ci/review.gitlab-ci.yml

@@ -69,7 +69,7 @@ review-build-cng:
   variables:
     HOST_SUFFIX: "${CI_ENVIRONMENT_SLUG}"
     DOMAIN: "-${CI_ENVIRONMENT_SLUG}.${REVIEW_APPS_DOMAIN}"
-    GITLAB_HELM_CHART_REF: "v2.5.1"
+    GITLAB_HELM_CHART_REF: "v2.6.8"
     GITLAB_EDITION: "ce"
   environment:
     name: review/${CI_COMMIT_REF_NAME}