Use newfeed.service config for all newsfeeds (#90252)

Co-authored-by: Alejandro Fernández Haro <afharo@gmail.com>
Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>

src/plugins/newsfeed/public/plugin.tsx

@@ -51,7 +51,10 @@ export class NewsfeedPublicPlugin
     return {
       createNewsFeed$: (endpoint: NewsfeedApiEndpoint) => {
         const config = Object.assign({}, this.config, {
-          service: { pathTemplate: `/${endpoint}/v{VERSION}.json` },
+          service: {
+            ...this.config.service,
+            pathTemplate: `/${endpoint}/v{VERSION}.json`,
+          },
         });
         return this.fetchNewsfeed(core, config);
       },