Remove project_level_issues_analytics FF

This change removes the project_level_issues_analytics feature flag.

Changelog: removed

ee/config/feature_flags/development/project_level_issues_analytics.yml

----
-name: project_level_issues_analytics
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/25417
-rollout_issue_url: 
-milestone: '12.9'
-type: development
-group: group::optimize
-default_enabled: true

ee/lib/ee/sidebars/projects/menus/analytics_menu.rb

@@ -65,8 +65,7 @@ module EE
           end
 
           def show_issues_analytics?
-            ::Feature.enabled?(:project_level_issues_analytics, context.project, default_enabled: true) &&
-              context.project.licensed_feature_available?(:issues_analytics) &&
+            context.project.licensed_feature_available?(:issues_analytics) &&
               can?(context.current_user, :read_project, context.project)
           end
 

ee/spec/lib/ee/sidebars/projects/menus/analytics_menu_spec.rb

@@ -50,10 +50,10 @@ RSpec.describe Sidebars::Projects::Menus::AnalyticsMenu do
 
     describe 'Issue' do
       let(:item_id) { :issues }
-      let(:flag_enabled) { true }
+      let(:licensed) { true }
 
       before do
-        stub_licensed_features(issues_analytics: flag_enabled)
+        stub_licensed_features(issues_analytics: licensed)
       end
 
       specify { is_expected.not_to be_nil }
@@ -64,16 +64,8 @@ RSpec.describe Sidebars::Projects::Menus::AnalyticsMenu do
         specify { is_expected.to be_nil }
       end
 
-      describe 'when feature flag :project_level_issues_analytics is not enabled' do
-        before do
-          stub_feature_flags(project_level_issues_analytics: false)
-        end
-
-        specify { is_expected.to be_nil }
-      end
-
       describe 'when licensed feature issues analytics is not enabled' do
-        let(:flag_enabled) { false }
+        let(:licensed) { false }
 
         specify { is_expected.to be_nil }
       end