Remove localVue Usage from Feature Flag Tests

They aren't being used, and aren't necessary in Jest.

ee/spec/frontend/feature_flags/components/configure_feature_flags_modal_spec.js

-import { shallowMount, createLocalVue } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import { GlButton } from '@gitlab/ui';
-import component from 'ee/feature_flags/components/configure_feature_flags_modal.vue';
-
-const localVue = createLocalVue();
+import Component from 'ee/feature_flags/components/configure_feature_flags_modal.vue';
 
 describe('Configure Feature Flags Modal', () => {
-  const Component = localVue.extend(component);
   let wrapper;
   let propsData;
 
@@ -24,7 +21,6 @@ describe('Configure Feature Flags Modal', () => {
 
     wrapper = shallowMount(Component, {
       propsData,
-      localVue,
       sync: false,
       attachToDocument: true,
     });

ee/spec/frontend/feature_flags/components/environments_dropdown_spec.js

 import MockAdapter from 'axios-mock-adapter';
-import { createLocalVue, shallowMount } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import { GlLoadingIcon, GlButton } from '@gitlab/ui';
 import EnvironmentsDropdown from 'ee/feature_flags/components/environments_dropdown.vue';
 import { TEST_HOST } from 'spec/test_constants';
 import axios from '~/lib/utils/axios_utils';
 
-const localVue = createLocalVue();
-
 describe('Feature flags > Environments dropdown ', () => {
   let wrapper;
   let mock;
 
   const factory = props => {
     wrapper = shallowMount(EnvironmentsDropdown, {
-      localVue,
       propsData: {
         endpoint: `${TEST_HOST}/environments.json'`,
         ...props,

ee/spec/frontend/feature_flags/components/feature_flags_spec.js

-import { createLocalVue, shallowMount } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import MockAdapter from 'axios-mock-adapter';
 import { GlEmptyState, GlLoadingIcon } from '@gitlab/ui';
 import store from 'ee/feature_flags/store';
@@ -11,8 +11,6 @@ import TablePagination from '~/vue_shared/components/pagination/table_pagination
 import axios from '~/lib/utils/axios_utils';
 import { getRequestData } from '../mock_data';
 
-const localVue = createLocalVue();
-
 describe('Feature flags', () => {
   const mockData = {
     endpoint: `${TEST_HOST}/endpoint.json`,
@@ -32,7 +30,6 @@ describe('Feature flags', () => {
 
   const factory = (propsData = mockData) => {
     wrapper = shallowMount(FeatureFlagsComponent, {
-      localVue,
       propsData,
       sync: false,
     });
@@ -148,7 +145,7 @@ describe('Feature flags', () => {
         it('renders disabled title', () => {
           wrapper.setData({ scope: 'disabled' });
 
-          return localVue.nextTick(() => {
+          return wrapper.vm.$nextTick(() => {
             expect(emptyState.props('title')).toEqual('There are no inactive feature flags');
           });
         });
@@ -158,7 +155,7 @@ describe('Feature flags', () => {
         it('renders enabled title', () => {
           wrapper.setData({ scope: 'enabled' });
 
-          localVue.nextTick(() => {
+          wrapper.vm.$nextTick(() => {
             expect(emptyState.props('title')).toEqual('There are no active feature flags');
           });
         });

ee/spec/frontend/feature_flags/components/feature_flags_table_spec.js

 import FeatureFlagsTable from 'ee/feature_flags/components/feature_flags_table.vue';
-import { createLocalVue, shallowMount } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import { GlToggle } from '@gitlab/ui';
 import { trimText } from 'helpers/text_helper';
 import {
@@ -8,8 +8,6 @@ import {
   DEFAULT_PERCENT_ROLLOUT,
 } from 'ee/feature_flags/constants';
 
-const localVue = createLocalVue();
-
 const getDefaultProps = () => ({
   featureFlags: [
     {
@@ -44,7 +42,6 @@ describe('Feature flag table', () => {
     wrapper = shallowMount(FeatureFlagsTable, {
       propsData,
       sync: false,
-      localVue,
       ...opts,
     });
   };

ee/spec/frontend/feature_flags/components/form_spec.js

 import _ from 'underscore';
-import { createLocalVue, shallowMount } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import { GlFormTextarea, GlFormCheckbox } from '@gitlab/ui';
 import Form from 'ee/feature_flags/components/form.vue';
 import EnvironmentsDropdown from 'ee/feature_flags/components/environments_dropdown.vue';
@@ -31,10 +31,7 @@ describe('feature flag form', () => {
   });
 
   const factory = (props = {}) => {
-    const localVue = createLocalVue();
-
     wrapper = shallowMount(Form, {
-      localVue,
       propsData: props,
       provide: {
         glFeatures: {

ee/spec/frontend/feature_flags/components/new_feature_flag_spec.js

 import Vuex from 'vuex';
-import { createLocalVue, shallowMount } from '@vue/test-utils';
+import { shallowMount } from '@vue/test-utils';
 import Form from 'ee/feature_flags/components/form.vue';
 import newModule from 'ee/feature_flags/store/modules/new';
 import NewFeatureFlag from 'ee/feature_flags/components/new_feature_flag.vue';
 import { ROLLOUT_STRATEGY_ALL_USERS, DEFAULT_PERCENT_ROLLOUT } from 'ee/feature_flags/constants';
 
-const localVue = createLocalVue();
-localVue.use(Vuex);
-
 describe('New feature flag form', () => {
   let wrapper;
 
@@ -19,7 +16,6 @@ describe('New feature flag form', () => {
 
   const factory = () => {
     wrapper = shallowMount(NewFeatureFlag, {
-      localVue,
       propsData: {
         endpoint: 'feature_flags.json',
         path: '/feature_flags',