Use links endpoint instead of related_issues

app/views/projects/issues/show.html.haml

@@ -5,6 +5,7 @@
 - can_update_issue = can?(current_user, :update_issue, @issue)
 - can_report_spam = @issue.submittable_as_spam_by?(current_user)
 - content_for :page_specific_javascripts do
+  = webpack_bundle_tag('common_vue')
   = webpack_bundle_tag('issuable')
 
 .clearfix.detail-page-header
@@ -67,7 +68,7 @@
 
       = edited_time_ago_with_tooltip(@issue, placement: 'bottom', html_class: 'issue-edited-ago js-issue-edited-ago')
 
-    .js-related-issues-root{ data: { endpoint: namespace_project_issue_related_issues_path(@project.namespace, @project, @issue),
+    .js-related-issues-root{ data: { endpoint: namespace_project_issue_links_path(@project.namespace, @project, @issue),
       namespace: @project.namespace.path,
       project: @project.path,
       can_add_related_issues: "#{can?(current_user, :update_issue, @issue)}",