Alerting: Fix using stacks- prefix instead of stack- for checking the namespace in boot data (grafana#97492)

* Fix using stacks- prefix instead of stack- for checking the namespace in config boot data

* use config directly for namespace

Author: soniaAguilarPeiron

public/app/features/alerting/unified/home/Insights.tsx

@@ -95,9 +95,9 @@ export const PANEL_STYLES = { minHeight: 300 };
 
 const THIS_WEEK_TIME_RANGE = new SceneTimeRange({ from: 'now-1w', to: 'now' });
 
-const namespace = config.bootData.settings.namespace;
+const namespace = config.namespace;
 
-export const INSTANCE_ID = namespace.includes('stack-') ? namespace.replace('stack-', '') : undefined;
+export const INSTANCE_ID = namespace.includes('stacks-') ? namespace.replace('stacks-', '') : undefined;
 
 const getInsightsDataSources = () => {
   const dataSourceSrv = getDataSourceSrv();