Refactor: Decouple Label Browser from LocalStorage (#40449)

* Refactor: Decouple Label Browser from LocalStorage

* Clean up

public/app/plugins/datasource/prometheus/components/PrometheusMetricsBrowser.test.tsx

@@ -133,6 +133,9 @@ describe('PrometheusMetricsBrowser', () => {
       onChange: () => {},
       autoSelect: 0,
       languageProvider: (mockLanguageProvider as unknown) as PromQlLanguageProvider,
+      lastUsedLabels: [],
+      storeLastUsedLabels: () => {},
+      deleteLastUsedLabels: () => {},
     };
 
     return defaults;