[dashboard] fix dashboard references lost when dashboard updated from listing page (#241381)

Closes #241350

`update` endpoint does not support partial updates. This PR is as small
as possible to resolve the regression by passing full state when
updating dashboard state from listing page. Other `update` endpoint
issues can be tracked in
#241380.

Author: nreese

src/platform/plugins/shared/dashboard/public/services/dashboard_content_management_service/lib/update_dashboard_meta.ts

@@ -38,8 +38,12 @@ export const updateDashboardMeta = async ({
   await contentManagementService.client.update<DashboardUpdateIn, DashboardUpdateOut>({
     contentTypeId: DASHBOARD_CONTENT_ID,
     id,
-    data: { title, description, tags },
-    options: { references: [] },
+    data: { ...dashboard.attributes, title, description, tags },
+    options: {
+      references: dashboard.references,
+      /** perform a "full" update instead, where the provided attributes will fully replace the existing ones */
+      mergeAttributes: false,
+    },
   });
 
   getDashboardContentManagementCache().deleteDashboard(id);