Fix epic swimlanes list drag drop reordering

We added a check to "moveList" vuex action
which serves as the handler for list Draggables in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/68126.

The check ensured that only move events fired by
list Draggables were handled by "moveList" by checking
for data-draggable-item-type attribute.

The attribute's been missing for epic swimlane columns
breaking the drag and drop reordering of lists in
epic swimlanes.

This commit adds the attribute to epic swimlane columns

Changelog: fixed
EE: true

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

@@ -11,7 +11,7 @@ import { s__, n__, __ } from '~/locale';
 import defaultSortableConfig from '~/sortable/sortable_config';
 import glFeatureFlagsMixin from '~/vue_shared/mixins/gl_feature_flags_mixin';
 import { calculateSwimlanesBufferSize } from '../boards_util';
-import { DRAGGABLE_TAG, EPIC_LANE_BASE_HEIGHT } from '../constants';
+import { DRAGGABLE_TAG, EPIC_LANE_BASE_HEIGHT, DraggableItemTypes } from '../constants';
 import EpicLane from './epic_lane.vue';
 import IssuesLaneList from './issues_lane_list.vue';
 import SwimlanesLoadingSkeleton from './swimlanes_loading_skeleton.vue';
@@ -19,6 +19,7 @@ import SwimlanesLoadingSkeleton from './swimlanes_loading_skeleton.vue';
 export default {
   EpicLane,
   epicLaneBaseHeight: EPIC_LANE_BASE_HEIGHT,
+  draggableItemTypes: DraggableItemTypes,
   components: {
     BoardAddNewColumn,
     BoardListHeader,
@@ -215,6 +216,7 @@ export default {
           class="board gl-display-inline-block gl-px-3 gl-vertical-align-top gl-white-space-normal"
           :data-list-id="list.id"
           data-testid="board-header-container"
+          :data-draggable-item-type="$options.draggableItemTypes.list"
         >
           <board-list-header
             :can-admin-list="canAdminList"

ee/spec/features/boards/swimlanes/epics_swimlanes_drag_issue_spec.rb → ee/spec/features/boards/swimlanes/epics_swimlanes_drag_drop_spec.rb

@@ -33,7 +33,7 @@ RSpec.describe 'epics swimlanes', :js do
     stub_licensed_features(epics: true, swimlanes: true)
 
     sign_in(user)
-    visit_board_page
+    load_board project_boards_path(project)
     load_epic_swimlanes
     load_unassigned_issues
   end
@@ -117,9 +117,24 @@ RSpec.describe 'epics swimlanes', :js do
     end
   end
 
-  def visit_board_page
-    visit project_boards_path(project)
-    wait_for_requests
+  context 'drag and drop list' do
+    let_it_be(:label2) { create(:label, project: project, name: 'Label 2') }
+    let_it_be(:list2) { create(:list, board: board, label: label2, position: 1) }
+
+    it 're-orders lists' do
+      drag(list_from_index: 1, list_to_index: 2, selector: '.board-header')
+
+      wait_for_requests
+
+      expect(find_board_list_header(2)).to have_content(label2.title)
+      expect(find_board_list_header(3)).to have_content(label.title)
+      expect(list.reload.position).to eq(1)
+      expect(list2.reload.position).to eq(0)
+    end
+  end
+
+  def find_board_list_header(list_idx)
+    find(".board:nth-child(#{list_idx}) [data-testid=\"board-list-header\"]")
   end
 
   def select_epics