fix(@schematics/angular): e2e should use the prefix

Now that the CLI repects the prefix specified, the generated e2e test should also use it.

Author: cexbrayat

packages/schematics/angular/e2e/files/src/app.e2e-spec.ts

@@ -9,6 +9,6 @@ describe('workspace-project App', () => {
 
   it('should display welcome message', () => {
     page.navigateTo();
-    expect(page.getParagraphText()).toEqual('Welcome to app!');
+    expect(page.getParagraphText()).toEqual('Welcome to <%= prefix %>!');
   });
 });