Simplify setting up apollo provider in spec

- https://gitlab.com/gitlab-org/gitlab/-/merge_requests/67995#note_651380375

ee/spec/frontend/security_configuration/dast_profiles/components/base_dast_profile_form_spec.js

 import { GlAlert, GlForm, GlModal } from '@gitlab/ui';
 import { createLocalVue } from '@vue/test-utils';
 import merge from 'lodash/merge';
-import { createMockClient } from 'mock-apollo-client';
 import VueApollo from 'vue-apollo';
 import BaseDastProfileForm from 'ee/security_configuration/dast_profiles/components/base_dast_profile_form.vue';
 import dastSiteProfileCreateMutation from 'ee/security_configuration/dast_profiles/dast_site_profiles/graphql/dast_site_profile_create.mutation.graphql';
 import { dastSiteProfileCreate } from 'ee_jest/security_configuration/dast_profiles/dast_site_profiles/mock_data/apollo_mock';
+import createMockApollo from 'helpers/mock_apollo_helper';
 import { shallowMountExtended } from 'helpers/vue_test_utils_helper';
 import waitForPromises from 'helpers/wait_for_promises';
 
@@ -23,11 +23,8 @@ const defaultProps = {
   modalProps: {},
 };
 
-const defaultRequestHandler = jest.fn().mockResolvedValue(dastSiteProfileCreate());
-
 describe('BaseDastProfileForm', () => {
   let wrapper;
-  let apolloProvider;
   let requestHandler;
 
   // Finders
@@ -45,22 +42,8 @@ describe('BaseDastProfileForm', () => {
   // Assertions
   const expectSubmitNotLoading = () => expect(findSubmitButton().props('loading')).toBe(false);
 
-  const mockClientFactory = (handler = defaultRequestHandler) => {
-    const mockClient = createMockClient();
-    mockClient.setRequestHandler(dastSiteProfileCreateMutation, handler);
-    requestHandler = handler;
-
-    return mockClient;
-  };
-
-  const withHandler = (handler) => {
-    apolloProvider.defaultClient = mockClientFactory(handler);
-  };
-
   const createComponent = (options) => {
-    apolloProvider = new VueApollo({
-      defaultClient: mockClientFactory(),
-    });
+    const apolloProvider = createMockApollo([[dastSiteProfileCreateMutation, requestHandler]]);
 
     const mountOpts = merge(
       {},
@@ -75,13 +58,15 @@ describe('BaseDastProfileForm', () => {
     );
 
     wrapper = shallowMountExtended(BaseDastProfileForm, mountOpts);
-
-    return { withHandler };
   };
 
+  beforeEach(() => {
+    // default request handler
+    requestHandler = jest.fn().mockResolvedValue(dastSiteProfileCreate());
+  });
+
   afterEach(() => {
     wrapper.destroy();
-    apolloProvider = null;
   });
 
   it('renders default slot', () => {
@@ -206,11 +191,12 @@ describe('BaseDastProfileForm', () => {
       const defaultErrorMessage = 'Default error message';
 
       beforeEach(async () => {
+        requestHandler.mockRejectedValue(new Error('GraphQL Network Error'));
         createComponent({
           slots: {
             'error-message': defaultErrorMessage,
           },
-        }).withHandler(jest.fn().mockRejectedValue(new Error('GraphQL Network Error')));
+        });
         submitForm();
         await waitForPromises();
       });
@@ -229,9 +215,10 @@ describe('BaseDastProfileForm', () => {
       const errors = ['error#1', 'error#2', 'error#3'];
 
       beforeEach(async () => {
+        requestHandler.mockResolvedValue(dastSiteProfileCreate(errors));
         createComponent({
           stubs: { GlAlert },
-        }).withHandler(jest.fn().mockResolvedValue(dastSiteProfileCreate(errors)));
+        });
         submitForm();
         await waitForPromises();
       });