Merge branch 'winh-board_form-showPage-ee' into 'master'

Use existing showPage() from BoardsStoreEE in BoardForm

See merge request gitlab-org/gitlab-ee!13243

ee/app/assets/javascripts/boards/components/board_form.vue

@@ -192,7 +192,7 @@ export default {
       }
     },
     cancel() {
-      boardsStore.state.currentPage = '';
+      boardsStore.showPage('');
     },
     resetFormState() {
       if (this.isNewForm) {