Remove incorrect localVue usage

localVue is required only with use method

spec/frontend/vue_shared/components/callout_spec.js

-import { createLocalVue, shallowMount } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import Callout from '~/vue_shared/components/callout.vue';
 
 const TEST_MESSAGE = 'This is a callout message!';
 const TEST_SLOT = '<button>This is a callout slot!</button>';
 
-const localVue = createLocalVue();
-
 describe('Callout Component', () => {
   let wrapper;
 
   const factory = options => {
-    wrapper = shallowMount(localVue.extend(Callout), {
-      localVue,
+    wrapper = shallowMount(Callout, {
       ...options,
     });
   };

spec/frontend/vue_shared/components/expand_button_spec.js

 import Vue from 'vue';
-import { mount, createLocalVue } from '@vue/test-utils';
+import { mount } from '@vue/test-utils';
 import ExpandButton from '~/vue_shared/components/expand_button.vue';
 
 const text = {
@@ -14,10 +14,7 @@ describe('Expand button', () => {
   const expanderAppendEl = () => wrapper.find('.js-text-expander-append');
 
   const factory = (options = {}) => {
-    const localVue = createLocalVue();
-
-    wrapper = mount(localVue.extend(ExpandButton), {
-      localVue,
+    wrapper = mount(ExpandButton, {
       ...options,
     });
   };

spec/frontend/vue_shared/components/issue/related_issuable_item_spec.js

 import Vue from 'vue';
-import { mount, createLocalVue } from '@vue/test-utils';
+import { mount } from '@vue/test-utils';
 import { formatDate } from '~/lib/utils/datetime_utility';
 import RelatedIssuableItem from '~/vue_shared/components/issue/related_issuable_item.vue';
 import {
@@ -29,10 +29,7 @@ describe('RelatedIssuableItem', () => {
   };
 
   beforeEach(() => {
-    const localVue = createLocalVue();
-
-    wrapper = mount(localVue.extend(RelatedIssuableItem), {
-      localVue,
+    wrapper = mount(RelatedIssuableItem, {
       slots,
       sync: false,
       attachToDocument: true,

spec/frontend/vue_shared/components/markdown/suggestion_diff_header_spec.js

 import { GlLoadingIcon } from '@gitlab/ui';
-import { shallowMount, createLocalVue } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import SuggestionDiffHeader from '~/vue_shared/components/markdown/suggestion_diff_header.vue';
 
-const localVue = createLocalVue();
-
 const DEFAULT_PROPS = {
   canApply: true,
   isApplied: false,
@@ -14,12 +12,11 @@ describe('Suggestion Diff component', () => {
   let wrapper;
 
   const createComponent = props => {
-    wrapper = shallowMount(localVue.extend(SuggestionDiffHeader), {
+    wrapper = shallowMount(SuggestionDiffHeader, {
       propsData: {
         ...DEFAULT_PROPS,
         ...props,
       },
-      localVue,
       sync: false,
       attachToDocument: true,
     });

spec/frontend/vue_shared/components/notes/system_note_spec.js

-import { createLocalVue, mount } from '@vue/test-utils';
+import { mount } from '@vue/test-utils';
 import IssueSystemNote from '~/vue_shared/components/notes/system_note.vue';
 import createStore from '~/notes/stores';
 import initMRPopovers from '~/mr_popover/index';
 
 jest.mock('~/mr_popover/index', () => jest.fn());
 
-const localVue = createLocalVue();
-
 describe('system note component', () => {
   let vm;
   let props;
@@ -34,7 +32,6 @@ describe('system note component', () => {
 
     vm = mount(IssueSystemNote, {
       store,
-      localVue,
       propsData: props,
       attachToDocument: true,
       sync: false,

spec/frontend/vue_shared/components/notes/timeline_entry_item_spec.js

-import { shallowMount, createLocalVue } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import TimelineEntryItem from '~/vue_shared/components/notes/timeline_entry_item.vue';
 
 describe(`TimelineEntryItem`, () => {
   let wrapper;
 
   const factory = (options = {}) => {
-    const localVue = createLocalVue();
-
     wrapper = shallowMount(TimelineEntryItem, {
-      localVue,
       ...options,
     });
   };

spec/frontend/vue_shared/components/pagination_links_spec.js

-import { mount, createLocalVue } from '@vue/test-utils';
+import { mount } from '@vue/test-utils';
 import { GlPagination } from '@gitlab/ui';
 import PaginationLinks from '~/vue_shared/components/pagination_links.vue';
 import {
@@ -10,8 +10,6 @@ import {
   LABEL_LAST_PAGE,
 } from '~/vue_shared/components/pagination/constants';
 
-const localVue = createLocalVue();
-
 describe('Pagination links component', () => {
   const pageInfo = {
     page: 3,
@@ -38,7 +36,6 @@ describe('Pagination links component', () => {
         change: changeMock,
         pageInfo,
       },
-      localVue,
       sync: false,
     });
   };

spec/frontend/vue_shared/components/time_ago_tooltip_spec.js

-import { shallowMount, createLocalVue } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import TimeAgoTooltip from '~/vue_shared/components/time_ago_tooltip.vue';
 import { formatDate, getTimeago } from '~/lib/utils/datetime_utility';
 
@@ -10,7 +10,6 @@ describe('Time ago with tooltip component', () => {
       attachToDocument: true,
       sync: false,
       propsData,
-      localVue: createLocalVue(),
     });
   };
   const timestamp = '2017-05-08T14:57:39.781Z';

spec/frontend/vue_shared/directives/track_event_spec.js

 import Vue from 'vue';
-import { createLocalVue, shallowMount } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import Tracking from '~/tracking';
 import TrackEvent from '~/vue_shared/directives/track_event';
 
@@ -17,15 +17,12 @@ const Component = Vue.component('dummy-element', {
   template: '<button id="trackable" v-track-event="trackingOptions"></button>',
 });
 
-const localVue = createLocalVue();
 let wrapper;
 let button;
 
 describe('Error Tracking directive', () => {
   beforeEach(() => {
-    wrapper = shallowMount(localVue.extend(Component), {
-      localVue,
-    });
+    wrapper = shallowMount(Component, {});
     button = wrapper.find('#trackable');
   });
 

spec/frontend/vue_shared/droplab_dropdown_button_spec.js

-import { mount, createLocalVue } from '@vue/test-utils';
+import { mount } from '@vue/test-utils';
 
 import DroplabDropdownButton from '~/vue_shared/components/droplab_dropdown_button.vue';
 
@@ -18,11 +18,8 @@ const createComponent = ({
   dropdownClass = '',
   actions = mockActions,
   defaultAction = 0,
-}) => {
-  const localVue = createLocalVue();
-
-  return mount(DroplabDropdownButton, {
-    localVue,
+}) =>
+  mount(DroplabDropdownButton, {
     propsData: {
       size,
       dropdownClass,
@@ -30,7 +27,6 @@ const createComponent = ({
       defaultAction,
     },
   });
-};
 
 describe('DroplabDropdownButton', () => {
   let wrapper;

spec/frontend/vue_shared/mixins/gl_feature_flags_mixin_spec.js

-import { createLocalVue, shallowMount } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import glFeatureFlagsMixin from '~/vue_shared/mixins/gl_feature_flags_mixin';
 
-const localVue = createLocalVue();
-
 describe('GitLab Feature Flags Mixin', () => {
   let wrapper;
 
@@ -20,7 +18,6 @@ describe('GitLab Feature Flags Mixin', () => {
     };
 
     wrapper = shallowMount(component, {
-      localVue,
       provide: {
         glFeatures: { ...(gon.features || {}) },
       },