docs: remove test.ts file in aio (#52327)

Same as 7ba5dc87ed, but for aio
This file is not necessary since CLI v15+

PR Close #52327

aio/angular.json

@@ -215,7 +215,6 @@
         "test": {
           "builder": "@angular-devkit/build-angular:karma",
           "options": {
-            "main": "src/test.ts",
             "polyfills": ["zone.js", "zone.js/testing"],
             "tsConfig": "tsconfig.spec.json",
             "webWorkerTsConfig": "tsconfig.worker.json",

aio/src/test.ts

@@ -1,14 +0,0 @@
-// This file is required by karma.conf.js and loads recursively all the .spec and framework files
-
-import 'zone.js/testing';
-import { getTestBed } from '@angular/core/testing';
-import {
-  BrowserDynamicTestingModule,
-  platformBrowserDynamicTesting
-} from '@angular/platform-browser-dynamic/testing';
-
-// First, initialize the Angular testing environment.
-getTestBed().initTestEnvironment(
-  BrowserDynamicTestingModule,
-  platformBrowserDynamicTesting(),
-);

aio/tsconfig.spec.json

@@ -7,9 +7,6 @@
       "node"
     ]
   },
-  "files": [
-    "src/test.ts",
-  ],
   "include": [
     "src/testing/**/*.ts",
     "src/**/*.spec.ts",