Remove todo for batching

- batching is done behind the scenes for graphql using
  https://www.apollographql.com/docs/link/links/batch-http/

ee/app/assets/javascripts/security_dashboard/components/selection_summary.vue

@@ -55,7 +55,6 @@ export default {
       this.dismissSelectedVulnerabilities();
     },
     dismissSelectedVulnerabilities() {
-      // TODO: Batch vulnerability dismissal with https://gitlab.com/gitlab-org/gitlab/-/issues/214376
       const promises = this.selectedVulnerabilities.map(vulnerability =>
         this.$apollo.mutate({
           mutation: dismissVulnerability,