Remove incorrect localVue usage

localVue is required only with use method

spec/frontend/notes/components/diff_discussion_header_spec.js

-import { mount, createLocalVue } from '@vue/test-utils';
+import { mount } from '@vue/test-utils';
 
 import createStore from '~/notes/stores';
 import diffDiscussionHeader from '~/notes/components/diff_discussion_header.vue';
@@ -18,11 +18,9 @@ describe('diff_discussion_header component', () => {
     window.mrTabs = {};
     store = createStore();
 
-    const localVue = createLocalVue();
     wrapper = mount(diffDiscussionHeader, {
       store,
       propsData: { discussion: discussionMock },
-      localVue,
       sync: false,
     });
   });

spec/frontend/notes/components/discussion_actions_spec.js

-import { shallowMount, mount, createLocalVue } from '@vue/test-utils';
+import { shallowMount, mount } from '@vue/test-utils';
 import { discussionMock } from '../../notes/mock_data';
 import DiscussionActions from '~/notes/components/discussion_actions.vue';
 import ReplyPlaceholder from '~/notes/components/discussion_reply_placeholder.vue';
@@ -22,12 +22,10 @@ const createUnallowedNote = () =>
 describe('DiscussionActions', () => {
   let wrapper;
   const createComponentFactory = (shallow = true) => props => {
-    const localVue = createLocalVue();
     const store = createStore();
     const mountFn = shallow ? shallowMount : mount;
 
     wrapper = mountFn(DiscussionActions, {
-      localVue,
       store,
       propsData: {
         discussion: discussionMock,

spec/frontend/notes/components/discussion_notes_spec.js

-import { shallowMount, createLocalVue } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import '~/behaviors/markdown/render_gfm';
 import { SYSTEM_NOTE } from '~/notes/constants';
 import DiscussionNotes from '~/notes/components/discussion_notes.vue';
@@ -9,8 +9,6 @@ import SystemNote from '~/vue_shared/components/notes/system_note.vue';
 import createStore from '~/notes/stores';
 import { noteableDataMock, discussionMock, notesDataMock } from '../../notes/mock_data';
 
-const localVue = createLocalVue();
-
 describe('DiscussionNotes', () => {
   let wrapper;
 
@@ -20,7 +18,6 @@ describe('DiscussionNotes', () => {
     store.dispatch('setNotesData', notesDataMock);
 
     wrapper = shallowMount(DiscussionNotes, {
-      localVue,
       store,
       propsData: {
         discussion: discussionMock,

spec/frontend/notes/components/discussion_reply_placeholder_spec.js

-import { shallowMount, createLocalVue } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import ReplyPlaceholder from '~/notes/components/discussion_reply_placeholder.vue';
 
-const localVue = createLocalVue();
 const buttonText = 'Test Button Text';
 
 describe('ReplyPlaceholder', () => {
@@ -11,7 +10,6 @@ describe('ReplyPlaceholder', () => {
 
   beforeEach(() => {
     wrapper = shallowMount(ReplyPlaceholder, {
-      localVue,
       propsData: {
         buttonText,
       },

spec/frontend/notes/components/discussion_resolve_button_spec.js

-import { createLocalVue, shallowMount } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import resolveDiscussionButton from '~/notes/components/discussion_resolve_button.vue';
 
 const buttonTitle = 'Resolve discussion';
 
 describe('resolveDiscussionButton', () => {
   let wrapper;
-  let localVue;
 
   const factory = options => {
-    localVue = createLocalVue();
     wrapper = shallowMount(resolveDiscussionButton, {
-      localVue,
       ...options,
     });
   };
@@ -69,7 +66,7 @@ describe('resolveDiscussionButton', () => {
 
     const button = wrapper.find({ ref: 'isResolvingIcon' });
 
-    localVue.nextTick(() => {
+    wrapper.vm.$nextTick(() => {
       expect(button.exists()).toEqual(false);
     });
   });

spec/frontend/notes/components/note_app_spec.js

 import $ from 'helpers/jquery';
 import AxiosMockAdapter from 'axios-mock-adapter';
 import Vue from 'vue';
-import { mount, createLocalVue } from '@vue/test-utils';
+import { mount } from '@vue/test-utils';
 import { setTestTimeout } from 'helpers/timeout';
 import axios from '~/lib/utils/axios_utils';
 import NotesApp from '~/notes/components/notes_app.vue';
@@ -48,7 +48,6 @@ describe('note_app', () => {
         notesData: mockData.notesDataMock,
         userData: mockData.userDataMock,
       };
-      const localVue = createLocalVue();
 
       return mount(
         {
@@ -63,7 +62,6 @@ describe('note_app', () => {
           attachToDocument: true,
           propsData,
           store,
-          localVue,
           sync: false,
         },
       );

spec/frontend/notes/components/note_edited_text_spec.js

-import { shallowMount, createLocalVue } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import NoteEditedText from '~/notes/components/note_edited_text.vue';
 
-const localVue = createLocalVue();
 const propsData = {
   actionText: 'Edited',
   className: 'foo-bar',
@@ -21,7 +20,6 @@ describe('NoteEditedText', () => {
 
   beforeEach(() => {
     wrapper = shallowMount(NoteEditedText, {
-      localVue,
       propsData,
       sync: false,
       attachToDocument: true,