Fix code example for Sentry JavaScript DataLoader()

It used a constructor syntax but this throws a `TypeError: Sentry.dataloaderIntegration is not a constructor`.

Author: thom4parisot

docs/platforms/javascript/common/configuration/integrations/dataloader.mdx

@@ -33,7 +33,7 @@ The `dataloaderIntegration` adds instrumentation for the `dataloader` library to
 
 ```javascript
 Sentry.init({
-  integrations: [new Sentry.dataloaderIntegration()],
+  integrations: [Sentry.dataloaderIntegration()],
 });
 ```