Remove jest.useFakeTimers from specs

We have fake timers enabled in Jest config.
No needs to enable them in specs.

ee/spec/frontend/approvals/components/branches_select_spec.js

@@ -42,7 +42,6 @@ describe('Branches Select', () => {
   };
 
   beforeEach(() => {
-    jest.useFakeTimers();
     jest
       .spyOn(Api, 'projectProtectedBranches')
       .mockReturnValue(Promise.resolve(TEST_PROTECTED_BRANCHES));

spec/frontend/custom_metrics/components/custom_metrics_form_fields_spec.js

@@ -152,7 +152,6 @@ describe('custom metrics form fields component', () => {
 
     describe('when query validation is in flight', () => {
       beforeEach(() => {
-        jest.useFakeTimers();
         mountComponent(
           { metricPersisted: true, ...makeFormData({ query: 'validQuery' }) },
           {

spec/frontend/ide/components/preview/clientside_spec.js

@@ -70,14 +70,6 @@ describe('IDE clientside preview', () => {
     });
   };
 
-  beforeAll(() => {
-    jest.useFakeTimers();
-  });
-
-  afterAll(() => {
-    jest.useRealTimers();
-  });
-
   afterEach(() => {
     wrapper.destroy();
   });

spec/frontend/monitoring/store/actions_spec.js

@@ -62,9 +62,6 @@ describe('Monitoring store actions', () => {
   beforeEach(() => {
     mock = new MockAdapter(axios);
 
-    // Mock `backOff` function to remove exponential algorithm delay.
-    jest.useFakeTimers();
-
     jest.spyOn(commonUtils, 'backOff').mockImplementation(callback => {
       const q = new Promise((resolve, reject) => {
         const stop = arg => (arg instanceof Error ? reject(arg) : resolve(arg));

spec/frontend/notes/old_notes_spec.js

@@ -33,7 +33,6 @@ gl.utils.disableButtonIfEmptyField = () => {};
 // eslint-disable-next-line jest/no-disabled-tests
 describe.skip('Old Notes (~/notes.js)', () => {
   beforeEach(() => {
-    jest.useFakeTimers();
     loadFixtures(fixture);
 
     // Re-declare this here so that test_setup.js#beforeEach() doesn't

spec/frontend/notes/stores/actions_spec.js

@@ -272,8 +272,6 @@ describe('Actions Notes Store', () => {
   });
 
   describe('poll', () => {
-    jest.useFakeTimers();
-
     beforeEach(done => {
       jest.spyOn(axios, 'get');
 

spec/frontend/smart_interval_spec.js

@@ -3,8 +3,6 @@ import { assignIn } from 'lodash';
 import waitForPromises from 'helpers/wait_for_promises';
 import SmartInterval from '~/smart_interval';
 
-jest.useFakeTimers();
-
 let interval;
 
 describe('SmartInterval', () => {