getState is synchronous

Unfortunately, the `getSerializedState` method still needs to be async since the `getDashboardState` method on the CM service is a promise. But this might change when we move reference handling to the server in #192758.

src/plugins/dashboard/public/dashboard_api/get_dashboard_api.ts

@@ -172,7 +172,7 @@ export function getDashboardApi({
       unifiedSearchManager.internalApi.panelsReload$
     ).pipe(debounceTime(0)),
     getSerializedState: async () => {
-      const { controlGroupReferences, dashboardState, panelReferences } = await getState();
+      const { controlGroupReferences, dashboardState, panelReferences } = getState();
       return getDashboardContentManagementService().getDashboardState({
         controlGroupReferences,
         currentState: dashboardState,