Add UI wait for labels_widget ff functionality

qa/qa/page/component/issuable/sidebar.rb

@@ -124,6 +124,15 @@ module QA
             click_element(:more_assignees_link)
           end
 
+          # When the labels_widget feature flag is enabled, wait until the labels widget appears
+          def wait_for_labels_widget_feature_flag
+            Support::Retrier.retry_until(max_duration: 60, reload_page: page, retry_on_exception: true, sleep_interval: 5) do
+              within_element(:labels_block) do
+                find_element(:edit_link)
+              end
+            end
+          end
+
           private
 
           def wait_assignees_block_finish_loading

qa/qa/specs/features/ee/browser_ui/2_plan/scoped_labels/editing_scoped_labels_spec.rb

@@ -2,7 +2,7 @@
 
 module QA
   # TODO: Remove :requires_admin when the `Runtime::Feature.enable` method call is removed
-  RSpec.describe 'Plan', :requires_admin, quarantine: { issue: 'https://gitlab.com/gitlab-org/gitlab/-/issues/345076', type: :flaky } do
+  RSpec.describe 'Plan', :requires_admin do
     describe 'Editing scoped labels on issues' do
       let(:initial_label) { 'animal::fox' }
       let(:new_label_same_scope) { 'animal::dolphin' }
@@ -43,6 +43,9 @@ module QA
         testcase: 'https://gitlab.com/gitlab-org/quality/testcases/-/quality/test_cases/1181'
       ) do
         Page::Project::Issue::Show.perform do |show|
+          # TODO: Remove this method when the `Runtime::Feature.enable` method call is removed
+          show.wait_for_labels_widget_feature_flag
+
           show.select_labels(
             [
               new_label_same_scope,