refactor(core): Remove ununsed Zone mock from testing internals. (#49873)

The last time it was used in was on the v10 branch.

PR Close #49873

packages/core/testing/src/ng_zone_mock.ts

@@ -1,34 +0,0 @@
-/**
- * @license
- * Copyright Google LLC All Rights Reserved.
- *
- * Use of this source code is governed by an MIT-style license that can be
- * found in the LICENSE file at https://angular.io/license
- */
-
-import {EventEmitter, Injectable, NgZone} from '@angular/core';
-
-
-/**
- * A mock implementation of {@link NgZone}.
- */
-@Injectable()
-export class MockNgZone extends NgZone {
-  override onStable: EventEmitter<any> = new EventEmitter(false);
-
-  constructor() {
-    super({enableLongStackTrace: false, shouldCoalesceEventChangeDetection: false});
-  }
-
-  override run(fn: Function): any {
-    return fn();
-  }
-
-  override runOutsideAngular(fn: Function): any {
-    return fn();
-  }
-
-  simulateZoneExit(): void {
-    this.onStable.emit(null);
-  }
-}

packages/core/testing/src/testing_internal.ts

@@ -9,4 +9,3 @@
 export {inject} from './test_bed';
 
 export * from './logger';
-export * from './ng_zone_mock';