Adjust epic management end-to-end test

This adjustment is needed due to a feature change. Now, the way we
relate issues to epics has changed, and so the test needed to be
updated accordingly.

This change is related to the following failure in the following
nightly pipeline:
https://gitlab.com/gitlab-org/quality/nightly/-/jobs/347826845

ee/app/assets/javascripts/related_items_tree/components/tree_item.vue

@@ -77,6 +77,7 @@ export default {
 <template>
   <li
     class="tree-item list-item pt-0 pb-0"
+    data-qa-selector="related_issue_item"
     :class="{
       'has-children': hasChildren,
       'item-expanded': childrenFlags[itemReference].itemExpanded,

qa/qa/ee/page/group/epic/show.rb

@@ -12,10 +12,6 @@ module QA
               element :title, required: true
             end
 
-            view 'app/assets/javascripts/vue_shared/components/issue/related_issuable_item.vue' do
-              element :remove_related_issue_button
-            end
-
             view 'ee/app/assets/javascripts/epic/components/epic_header.vue' do
               element :close_reopen_epic_button
             end
@@ -28,8 +24,12 @@ module QA
               element :add_issue_input
             end
 
-            view 'ee/app/assets/javascripts/related_issues/components/related_issues_block.vue' do
-              element :related_issuable_item
+            view 'ee/app/assets/javascripts/related_items_tree/components/tree_item.vue' do
+              element :related_issue_item
+            end
+
+            view 'ee/app/assets/javascripts/related_items_tree/components/tree_item_body.vue' do
+              element :remove_issue_button
             end
 
             view 'ee/app/assets/javascripts/related_issues/constants.js' do
@@ -49,7 +49,9 @@ module QA
             end
 
             def remove_issue_from_epic
-              click_element :remove_related_issue_button
+              click_element :remove_issue_button
+              # Capybara code is used below due to the modal being defined in the @gitlab/ui project
+              find('#item-remove-confirmation___BV_modal_footer_ .btn-danger').click
             end
 
             def click_edit_button
@@ -66,12 +68,12 @@ module QA
               click_element :close_reopen_epic_button
             end
 
-            def has_related_issuable_item?
-              has_element?(:related_issuable_item)
+            def has_related_issue_item?
+              has_element?(:related_issue_item)
             end
 
-            def has_no_related_issuable_item?
-              has_no_element?(:related_issuable_item)
+            def has_no_related_issue_item?
+              has_no_element?(:related_issue_item)
             end
           end
         end

qa/qa/specs/features/ee/browser_ui/2_plan/epic/epics_management_spec.rb

@@ -44,11 +44,11 @@ module QA
           EE::Page::Group::Epic::Show.perform do |show|
             show.add_issue_to_epic(issue.web_url)
 
-            expect(show).to have_related_issuable_item
+            expect(show).to have_related_issue_item
 
             show.remove_issue_from_epic
 
-            expect(show).to have_no_related_issuable_item
+            expect(show).to have_no_related_issue_item
           end
         end