Remove feature flag for design management reference filter

This completes the release of the design reference filter

changelogs/unreleased/ajk-remove-design_management_reference_filter_gfm_pipeline-ff.yml

+---
+title: Enable design management reference filter
+merge_request: 43731
+author:
+type: added

config/feature_flags/development/design_management_reference_filter_gfm_pipeline.yml

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

doc/user/project/issues/design_management.md

@@ -263,10 +263,7 @@ Feature.disable(:design_management_todo_button)
 ## Referring to designs in Markdown
 
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/217160) in **GitLab 13.1**.
-> - It is deployed behind a feature flag, disabled by default.
-> - It is disabled on GitLab.com.
-> - It is not recommended for production use.
-> - To use it in GitLab self-managed instances, ask a GitLab administrator to [enable it](#enable-or-disable-design-references). **(CORE ONLY)**
+> - [Feature flag removed](https://gitlab.com/gitlab-org/gitlab/-/issues/258662) in **GitLab 13.5**
 
 We support referring to designs in [Markdown](../../markdown.md), which is available
 throughout the application, including in merge request and issue descriptions, in discussions and comments, and in wiki pages.
@@ -282,25 +279,6 @@ This will be rendered as:
 
 > See [#123[homescreen.png]](https://gitlab.com/your-group/your-project/-/issues/123/designs/homescreen.png)
 
-### Enable or disable design references **(CORE ONLY)**
-
-Design reference parsing 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 disable it for your instance.
-
-To disable it:
-
-```ruby
-Feature.disable(:design_management_reference_filter_gfm_pipeline)
-```
-
-To re-enable it:
-
-```ruby
-Feature.enable(:design_management_reference_filter_gfm_pipeline)
-```
-
 ## Design activity records
 
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/33051) in GitLab 13.1.

lib/banzai/filter/design_reference_filter.rb

@@ -3,8 +3,6 @@
 module Banzai
   module Filter
     class DesignReferenceFilter < AbstractReferenceFilter
-      FEATURE_FLAG = :design_management_reference_filter_gfm_pipeline
-
       class Identifier
         include Comparable
         attr_reader :issue_iid, :filename
@@ -35,14 +33,6 @@ module Banzai
 
       self.reference_type = :design
 
-      # This filter must be enabled by setting the
-      # design_management_reference_filter_gfm_pipeline flag
-      def call
-        return doc unless enabled?
-
-        super
-      end
-
       def find_object(project, identifier)
         records_per_parent[project][identifier]
       end
@@ -112,10 +102,6 @@ module Banzai
           .in_groups_of(100, false) # limitation of by_issue_id_and_filename, so we batch
           .flat_map { |ids| DesignManagement::Design.by_issue_id_and_filename(ids) }
       end
-
-      def enabled?
-        Feature.enabled?(FEATURE_FLAG, parent, default_enabled: true)
-      end
     end
   end
 end

spec/features/projects/issues/design_management/user_links_to_designs_in_issue_spec.rb

@@ -90,34 +90,5 @@ RSpec.describe 'viewing issues with design references' do
         expect(page).not_to have_link(design_ref_b)
       end
     end
-
-    context 'design management is enabled, but the filter is disabled globally' do
-      before do
-        enable_design_management
-        stub_feature_flags(
-          Banzai::Filter::DesignReferenceFilter::FEATURE_FLAG => false
-        )
-      end
-
-      it 'processes design tab links successfully, and design references as issue references', :aggregate_failures do
-        visit_page_with_design_references
-
-        expect(page).to have_text('The designs I mentioned')
-        expect(page).to have_link(design_tab_ref)
-        expect(page).to have_link(issue_ref)
-        expect(page).not_to have_link(design_ref_a)
-        expect(page).not_to have_link(design_ref_b)
-      end
-    end
-
-    context 'design management is enabled, and the filter is enabled for the current project' do
-      before do
-        stub_feature_flags(
-          Banzai::Filter::DesignReferenceFilter::FEATURE_FLAG => public_project
-        )
-      end
-
-      it_behaves_like 'successful use of design link references'
-    end
   end
 end

spec/lib/banzai/filter/design_reference_filter_spec.rb

@@ -74,26 +74,6 @@ RSpec.describe Banzai::Filter::DesignReferenceFilter do
 
         it_behaves_like 'a no-op filter'
       end
-
-      context 'design reference filter is not enabled' do
-        before do
-          stub_feature_flags(described_class::FEATURE_FLAG => false)
-        end
-
-        it_behaves_like 'a no-op filter'
-
-        it 'issues no queries' do
-          expect { process(input_text) }.not_to exceed_query_limit(0)
-        end
-      end
-
-      context 'the filter is enabled for the context project' do
-        before do
-          stub_feature_flags(described_class::FEATURE_FLAG => project)
-        end
-
-        it_behaves_like 'a good link reference'
-      end
     end
   end