docs(demos): fix demos to have same class name and remove files that aren't needed anymore

references #5311

demos/scroll/index.ts

@@ -3,8 +3,4 @@ import {App} from 'ionic/ionic';
 @App({
   templateUrl: 'main.html'
 })
-
-class DemoApp {
-  blur() {
-  }
-}
+class ApiDemoApp {}