test: move mockWarn into setup files

packages/server-renderer/__tests__/renderToStream.spec.ts

@@ -10,14 +10,11 @@ import {
   createTextVNode,
   createStaticVNode
 } from 'vue'
-import { escapeHtml, mockWarn } from '@vue/shared'
+import { escapeHtml } from '@vue/shared'
 import { renderToStream as _renderToStream } from '../src/renderToStream'
 import { Readable } from 'stream'
 import { ssrRenderSlot } from '../src/helpers/ssrRenderSlot'
 import { ssrRenderComponent } from '../src/helpers/ssrRenderComponent'
-
-mockWarn()
-
 const promisifyStream = (stream: Readable) => {
   return new Promise((resolve, reject) => {
     let result = ''

packages/server-renderer/__tests__/renderToString.spec.ts

@@ -10,13 +10,10 @@ import {
   createTextVNode,
   createStaticVNode
 } from 'vue'
-import { escapeHtml, mockWarn } from '@vue/shared'
+import { escapeHtml } from '@vue/shared'
 import { renderToString } from '../src/renderToString'
 import { ssrRenderSlot, SSRSlot } from '../src/helpers/ssrRenderSlot'
 import { ssrRenderComponent } from '../src/helpers/ssrRenderComponent'
-
-mockWarn()
-
 describe('ssr: renderToString', () => {
   test('should apply app context', async () => {
     const app = createApp({

packages/server-renderer/__tests__/ssrSuspense.spec.ts

@@ -1,10 +1,7 @@
 import { createApp, h, Suspense } from 'vue'
 import { renderToString } from '../src/renderToString'
-import { mockWarn } from '@vue/shared'
 
 describe('SSR Suspense', () => {
-  mockWarn()
-
   const ResolvingAsync = {
     async setup() {
       return () => h('div', 'async')