Remove affix plugin from issuable sidebar with new navigation

This isn't required with the new navigation as it is always position fixed so we are just creating a scroll event listener that will never actually do anything

app/assets/javascripts/sidebar_height_manager.js

 import _ from 'underscore';
+import Cookies from 'js-cookie';
 
 export default {
   init() {
     if (!this.initialized) {
+      if (Cookies.get('new_nav') === 'true' && $('.js-issuable-sidebar').length) return;
+
       this.$window = $(window);
       this.$rightSidebar = $('.js-right-sidebar');
       this.$navHeight = $('.navbar-gitlab').outerHeight() +

app/views/shared/issuable/_sidebar.html.haml

@@ -3,7 +3,7 @@
   = page_specific_javascript_bundle_tag('common_vue')
   = page_specific_javascript_bundle_tag('sidebar')
 
-%aside.right-sidebar.js-right-sidebar{ data: { "offset-top" => "50", "spy" => "affix", signed: { in: current_user.present? } }, class: sidebar_gutter_collapsed_class, 'aria-live' => 'polite' }
+%aside.right-sidebar.js-right-sidebar.js-issuable-sidebar{ data: { "offset-top" => ("50" unless show_new_nav?), "spy" => ("affix" unless show_new_nav?), signed: { in: current_user.present? } }, class: sidebar_gutter_collapsed_class, 'aria-live' => 'polite' }
   .issuable-sidebar{ data: { endpoint: "#{issuable_json_path(issuable)}" } }
     - can_edit_issuable = can?(current_user, :"admin_#{issuable.to_ability_name}", @project)
     .block.issuable-sidebar-header