Prevent loading of legacy sidebar on epic and graphQL boards

app/views/shared/boards/_show.html.haml

@@ -4,7 +4,8 @@
 - @no_container = true
 - @content_wrapper_class = "#{@content_wrapper_class} gl-relative"
 - @content_class = "issue-boards-content js-focus-mode-board"
-- if board.to_type == "EpicBoard"
+- is_epic_board = board.to_type == "EpicBoard"
+- if is_epic_board
   - breadcrumb_title _("Epic Boards")
 - else
   - breadcrumb_title _("Issue Boards")
@@ -19,5 +20,6 @@
 = render 'shared/issuable/search_bar', type: :boards, board: board
 #board-app.boards-app.position-relative{ "v-cloak" => "true", data: board_data, ":class" => "{ 'is-compact': detailIssueVisible }" }
   %board-content{ ":lists" => "state.lists", ":disabled" => "disabled" }
-  = render "shared/boards/components/sidebar", group: group
+  - if !is_epic_board && !Feature.enabled?(:graphql_board_lists, default_enabled: :yaml)
+    = render "shared/boards/components/sidebar", group: group
   %board-settings-sidebar

ee/app/assets/javascripts/epic_boards/index.js

@@ -9,7 +9,6 @@ import { mapActions, mapState } from 'vuex';
 
 import initFilteredSearch from 'ee/boards/epic_filtered_search';
 import { fullEpicBoardId, transformBoardConfig } from 'ee_component/boards/boards_util';
-import BoardSidebar from 'ee_component/boards/components/board_sidebar';
 import toggleLabels from 'ee_component/boards/toggle_labels';
 
 import BoardAddNewColumnTrigger from '~/boards/components/board_add_new_column_trigger.vue';
@@ -63,7 +62,6 @@ export default () => {
     el: $boardApp,
     components: {
       BoardContent,
-      BoardSidebar,
       BoardSettingsSidebar: () => import('~/boards/components/board_settings_sidebar.vue'),
     },
     provide: {