Explore: Avoid sending panelId header unless we are in a dashboard (#88255)

packages/grafana-runtime/src/utils/DataSourceWithBackend.ts

@@ -231,10 +231,10 @@ class DataSourceWithBackend<
 
     if (request.dashboardUID) {
       headers[PluginRequestHeaders.DashboardUID] = request.dashboardUID;
-    }
       if (request.panelId) {
         headers[PluginRequestHeaders.PanelID] = `${request.panelId}`;
       }
+    }
     if (request.panelPluginId) {
       headers[PluginRequestHeaders.PanelPluginId] = `${request.panelPluginId}`;
     }