Add DAST pages to grafonnet dashboard
2nd part of gitlab-org/gitlab#321744 (closed) which adds a row for DAST to https://dashboards.gitlab.net/d/product-secure/product-performance-secure?orgId=1
2nd part of gitlab-org/gitlab#321744 (closed) which adds a row for DAST to https://dashboards.gitlab.net/d/product-secure/product-performance-secure?orgId=1