style: datatrails: indicate prometheus data source (#83199)

* style: indicate prometheus data source

public/app/features/trails/DataTrail.tsx

@@ -29,7 +29,7 @@ import { MetricScene } from './MetricScene';
 import { MetricSelectScene } from './MetricSelectScene';
 import { MetricsHeader } from './MetricsHeader';
 import { getTrailStore } from './TrailStore/TrailStore';
-import { LOGS_METRIC, MetricSelectedEvent, trailDS, VAR_DATASOURCE, VAR_FILTERS } from './shared';
+import { MetricSelectedEvent, trailDS, VAR_DATASOURCE, VAR_FILTERS } from './shared';
 import { getUrlForTrail } from './utils';
 
 export interface DataTrailState extends SceneObjectState {
@@ -206,9 +206,9 @@ function getVariableSet(initialDS?: string, metric?: string, initialFilters?: Ad
     variables: [
       new DataSourceVariable({
         name: VAR_DATASOURCE,
-        label: 'Data source',
+        label: 'Prometheus data source',
         value: initialDS,
-        pluginId: metric === LOGS_METRIC ? 'loki' : 'prometheus',
+        pluginId: 'prometheus',
       }),
       new AdHocFiltersVariable({
         name: VAR_FILTERS,