build: move rxjs type reference to event emitter (#28720)

PR Close #28720

packages/common/http/testing/test/request_spec.ts

@@ -6,8 +6,6 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-/// <reference types="rxjs" />
-
 import {HttpClient} from '@angular/common/http';
 import {HttpClientTestingBackend} from '@angular/common/http/testing/src/backend';
 

packages/core/src/event_emitter.ts

@@ -6,6 +6,8 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+/// <reference types="rxjs" />
+
 import {Subject, Subscription} from 'rxjs';
 
 /**

packages/core/test/render3/outputs_spec.ts

@@ -6,8 +6,6 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-/// <reference types="rxjs" />
-
 import {EventEmitter} from '@angular/core';
 
 import {defineComponent, defineDirective} from '../../src/render3/index';

packages/core/test/render3/properties_spec.ts

@@ -6,8 +6,6 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-/// <reference types="rxjs" />
-
 import {EventEmitter} from '@angular/core';
 
 import {defineComponent, defineDirective} from '../../src/render3/index';

packages/core/test/render3/query_spec.ts

@@ -6,8 +6,6 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-/// <reference types="rxjs" />
-
 import {NgForOfContext} from '@angular/common';
 import {ElementRef, QueryList, TemplateRef, ViewContainerRef} from '@angular/core';