[dashboard] Remove last unused feature flag references (#20121)

Author: geropl

components/dashboard/src/data/featureflag-query.ts

@@ -23,10 +23,7 @@ const featureFlags = {
     repositoryFinderSearch: false,
     // dummy specified dataops feature, default false
     dataops: false,
-    // Logging tracing for added for investigate hanging issue
-    dashboard_logging_tracing: false,
     showBrowserExtensionPromotion: false,
-    usage_update_scheduler_duration: "15m",
     enable_experimental_jbtb: false,
 };