Move custom metrics Vue files out of EE

The Custom metrics feature is being moved into GitLab Core.

ee/app/assets/javascripts/monitoring/components/dashboard.vue

 <script>
-import CustomMetricsFormFields from 'ee/custom_metrics/components/custom_metrics_form_fields.vue';
+import CustomMetricsFormFields from '~/custom_metrics/components/custom_metrics_form_fields.vue';
 import CeDashboard from '~/monitoring/components/dashboard.vue';
 import AlertWidget from './alert_widget.vue';
 

ee/app/assets/javascripts/monitoring/components/panel_type.vue

 <script>
 import { mapGetters } from 'vuex';
-import CustomMetricsFormFields from 'ee/custom_metrics/components/custom_metrics_form_fields.vue';
+import CustomMetricsFormFields from '~/custom_metrics/components/custom_metrics_form_fields.vue';
 import CePanelType from '~/monitoring/components/panel_type.vue';
 import AlertWidget from './alert_widget.vue';
 

ee/app/assets/javascripts/pages/projects/prometheus/metrics/edit/index.js

-import customMetrics from 'ee/custom_metrics';
+import customMetrics from '~/custom_metrics';
 
 document.addEventListener('DOMContentLoaded', customMetrics);

ee/app/assets/javascripts/pages/projects/prometheus/metrics/new/index.js

-import customMetrics from 'ee/custom_metrics';
+import customMetrics from '~/custom_metrics';
 
 document.addEventListener('DOMContentLoaded', customMetrics);

ee/spec/frontend/monitoring/components/dashboard_spec.js

@@ -9,7 +9,7 @@ import {
 } from '../../../../../spec/frontend/monitoring/mock_data';
 import { getJSONFixture } from '../../../../../spec/frontend/helpers/fixtures';
 import { propsData } from '../../../../../spec/frontend/monitoring/init_utils';
-import CustomMetricsFormFields from 'ee/custom_metrics/components/custom_metrics_form_fields.vue';
+import CustomMetricsFormFields from '~/custom_metrics/components/custom_metrics_form_fields.vue';
 import Tracking from '~/tracking';
 import { createStore } from '~/monitoring/stores';
 import axios from '~/lib/utils/axios_utils';

qa/qa/ee/page/project/operations/metrics/show.rb

@@ -22,7 +22,7 @@ module QA
                     element :add_metric_button
                   end
 
-                  view 'ee/app/assets/javascripts/custom_metrics/components/custom_metrics_form_fields.vue' do
+                  view 'app/assets/javascripts/custom_metrics/components/custom_metrics_form_fields.vue' do
                     element :custom_metric_prometheus_title_field
                     element :custom_metric_prometheus_query_field
                     element :custom_metric_prometheus_y_label_field

ee/spec/frontend/custom_metrics/components/custom_metrics_form_fields_spec.js → spec/frontend/custom_metrics/components/custom_metrics_form_fields_spec.js

@@ -2,7 +2,7 @@ import { mount } from '@vue/test-utils';
 import MockAdapter from 'axios-mock-adapter';
 import { TEST_HOST } from 'helpers/test_constants';
 import waitForPromises from 'helpers/wait_for_promises';
-import CustomMetricsFormFields from 'ee/custom_metrics/components/custom_metrics_form_fields.vue';
+import CustomMetricsFormFields from '~/custom_metrics/components/custom_metrics_form_fields.vue';
 import axios from '~/lib/utils/axios_utils';
 
 const { CancelToken } = axios;

ee/spec/frontend/custom_metrics/components/custom_metrics_form_spec.js → spec/frontend/custom_metrics/components/custom_metrics_form_spec.js

 import { shallowMount } from '@vue/test-utils';
-import CustomMetricsForm from 'ee/custom_metrics/components/custom_metrics_form.vue';
+import CustomMetricsForm from '~/custom_metrics/components/custom_metrics_form.vue';
 
 describe('CustomMetricsForm', () => {
   let wrapper;