Properly overwrite the BoardPromotionState in Enterprise

Apparenly dynamic imports don't work properly. Let's just overwrite it
in the Enterprise version.

app/assets/javascripts/boards/components/board_column.vue

@@ -5,6 +5,7 @@ import { GlButtonGroup, GlButton, GlLabel, GlTooltip, GlIcon } from '@gitlab/ui'
 import isWipLimitsOn from 'ee_else_ce/boards/mixins/is_wip_limits';
 import { s__, __, sprintf } from '~/locale';
 import Tooltip from '~/vue_shared/directives/tooltip';
+import EmptyComponent from '~/vue_shared/components/empty_component';
 import AccessorUtilities from '../../lib/utils/accessor';
 import BoardBlankState from './board_blank_state.vue';
 import BoardDelete from './board_delete';
@@ -17,7 +18,7 @@ import { isScopedLabel } from '~/lib/utils/common_utils';
 
 export default {
   components: {
-    BoardPromotionState: () => import('ee_component/boards/components/board_promotion_state.vue'),
+    BoardPromotionState: EmptyComponent,
     BoardBlankState,
     BoardDelete,
     BoardList,

ee/app/assets/javascripts/boards/components/board_column.vue

@@ -3,8 +3,12 @@ import { mapActions } from 'vuex';
 import BoardColumnFoss from '~/boards/components/board_column.vue';
 import { __, sprintf, s__ } from '~/locale';
 import boardsStore from '~/boards/stores/boards_store';
+import BoardPromotionState from 'ee/boards/components/board_promotion_state';
 
 export default {
+  components: {
+    BoardPromotionState,
+  },
   extends: BoardColumnFoss,
   data() {
     return {

ee/spec/frontend/boards/components/board_column_spec.js

@@ -10,6 +10,10 @@ import axios from '~/lib/utils/axios_utils';
 import { TEST_HOST } from 'helpers/test_constants';
 import { listObj } from 'jest/boards/mock_data';
 
+// board_promotion_state tries to mount on the real DOM,
+// so we are mocking it in this test
+jest.mock('ee/boards/components/board_promotion_state', () => ({}));
+
 describe('Board Column Component', () => {
   let wrapper;
   let axiosMock;