Remove feature_flag_issue_links feature flag

Remove specs for flag

app/views/projects/feature_flags/edit.html.haml

-- @gfm_form = Feature.enabled?(:feature_flags_issue_links, @project, default_enabled: true)
+- @gfm_form = true
 
 - add_to_breadcrumbs s_('FeatureFlags|Feature Flags'), project_feature_flags_path(@project)
 - breadcrumb_title @feature_flag.name

doc/operations/feature_flags.md

@@ -352,32 +352,8 @@ end
 
 ## Feature Flag Related Issues **(PREMIUM)**
 
-> - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/36617) in GitLab 13.2.
-> - It's deployed behind a feature flag, enabled by default.
-> - It's enabled on GitLab.com.
-> - It can't be enabled or disabled per-project
-> - It's recommended for production use.
-> - For GitLab self-managed instances, GitLab administrators can opt to disable it.
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/36617) in GitLab 13.2.
 
 You can link related issues to a feature flag. In the **Linked issues** section, click the `+` button and input the issue reference number or the full URL of the issue.
 
 This feature is similar to the [related issues](../user/project/issues/related_issues.md) feature.
-
-### Enable or disable Feature Flag Related Issues **(CORE ONLY)**
-
-Feature Flag Related Issues is under development but ready for production use.
-It is deployed behind a feature flag that is **enabled by default**.
-[GitLab administrators with access to the GitLab Rails console](../administration/feature_flags.md)
-can opt to disable it for your instance.
-
-To disable it:
-
-```ruby
-Feature.disable(:feature_flags_issue_links)
-```
-
-To enable it:
-
-```ruby
-Feature.enable(:feature_flags_issue_links)
-```

ee/app/controllers/projects/feature_flag_issues_controller.rb

@@ -4,7 +4,6 @@ module Projects
   class FeatureFlagIssuesController < Projects::ApplicationController
     include IssuableLinks
 
-    before_action :ensure_feature_enabled!
     before_action :authorize_admin_feature_flags_issue_links!
 
     private
@@ -28,9 +27,5 @@ module Projects
     def feature_flag
       project.operations_feature_flags.find_by_iid(params[:feature_flag_iid])
     end
-
-    def ensure_feature_enabled!
-      render_404 unless Feature.enabled?(:feature_flags_issue_links, project, default_enabled: true)
-    end
   end
 end

ee/app/helpers/feature_flags_helper.rb

@@ -12,7 +12,7 @@ module FeatureFlagsHelper
   end
 
   def feature_flag_issues_links_endpoint(project, feature_flag, user)
-    return '' unless Feature.enabled?(:feature_flags_issue_links, project, default_enabled: true) && can?(user, :admin_feature_flags_issue_links, project)
+    return '' unless can?(user, :admin_feature_flags_issue_links, project)
 
     project_feature_flag_issues_path(project, feature_flag)
   end

ee/config/feature_flags/development/feature_flags_issue_links.yml

----
-name: feature_flags_issue_links
-introduced_by_url: 
-rollout_issue_url: 
-group: 
-type: development
-default_enabled: true

ee/spec/controllers/projects/feature_flag_issues_controller_spec.rb

@@ -162,16 +162,6 @@ RSpec.describe Projects::FeatureFlagIssuesController do
       expect(json_response.map { |issue| issue['id'] }).to eq([issue_b.id])
     end
 
-    it 'returns not found when the feature is off' do
-      stub_feature_flags(feature_flags_issue_links: false)
-      feature_flag, _, _ = setup
-      sign_in(developer)
-
-      get_request(project, feature_flag)
-
-      expect(response).to have_gitlab_http_status(:not_found)
-    end
-
     context 'when feature flag related issues feature is unlicensed' do
       before do
         stub_licensed_features(feature_flags_related_issues: false)

ee/spec/features/projects/feature_flags/feature_flag_issues_spec.rb

@@ -60,19 +60,6 @@ RSpec.describe 'Feature flag issue links', :js do
       end
     end
 
-    context 'when the feature is disabled' do
-      before do
-        stub_feature_flags(feature_flags_issue_links: false)
-      end
-
-      it 'does not show the related issues widget' do
-        visit(edit_project_feature_flag_path(project, feature_flag))
-
-        expect(page).to have_text 'Strategies'
-        expect(page).not_to have_selector '#related-issues'
-      end
-    end
-
     context 'when the feature is unlicensed' do
       before do
         stub_licensed_features(feature_flags_related_issues: false)

ee/spec/helpers/feature_flags_helper_spec.rb

@@ -22,12 +22,6 @@ RSpec.describe FeatureFlagsHelper do
   describe '#feature_flag_issues_links_endpoint' do
     subject { helper.feature_flag_issues_links_endpoint(project, feature_flag, user) }
 
-    it 'returns an empty string when the feature flag is disabled' do
-      stub_feature_flags(feature_flags_issue_links: false)
-
-      is_expected.to be_empty
-    end
-
     it 'returns an empty string when the user is not allowed' do
       allow(helper).to receive(:can?).with(user, :admin_feature_flags_issue_links, project).and_return(false)