Revert "docs(docs-infra): fix first-app intro example (#61042)" (#61145)

This reverts commit ab91a355f8.

Revert reason: the change causes CI to fail (the `lint` CI job).

PR Close #61145

adev/src/content/tutorials/first-app/intro/app.component.ts

@@ -1,9 +0,0 @@
-import {Component} from '@angular/core';
-
-@Component({
-  selector: 'app-root',
-  template: `
-    Welcome to Angular!
-  `,
-})
-export class AppComponent {}

adev/src/content/tutorials/first-app/intro/config.json

@@ -1,6 +1,7 @@
 {
   "title": "Your first Angular app",
   "type": "editor",
-  "nextTutorial": "first-app",
-  "openFiles": ["app.component.ts"]
+  "src": "../steps/14-http/src",
+  "nextTutorial": "learn-angular",
+  "openFiles": ["src/app/app.component.ts"]
 }