Revert "Add feature flag for design notification change"

This reverts commit 8eee9f52a99f38a581074729826aaff17d361074.

app/models/design_management/design.rb

@@ -146,12 +146,6 @@ module DesignManagement
       strong_memoize(:most_recent_action) { actions.ordered.last }
     end
 
-    def participants(current_user = nil)
-      return [] unless Feature.enabled?(:design_management_design_notification_participants, project)
-
-      super
-    end
-
     # A reference for a design is the issue reference, indexed by the filename
     # with an optional infix when full.
     #

config/feature_flags/development/design_management_design_notification_participants.yml

----
-name: design_management_design_notification_participants
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/46642
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/277319
-milestone: '13.6'
-type: development
-group: group::knowledge
-default_enabled: false

doc/user/profile/notifications.md

@@ -213,14 +213,7 @@ then that user will also be notified.
 
 ## Design email notifications
 
-> - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/217095) in GitLab 13.6.
-> - It's [deployed behind a feature flag](../../user/feature_flags.md), disabled by default.
-> - It's disabled on GitLab.com.
-> - It's not recommended for production use.
-> - To use it in GitLab self-managed instances, ask a GitLab administrator to [enable it](#enable-or-disable-design-email-notifications). **(CORE ONLY)**
-
-CAUTION: **Warning:**
-This feature might not be available to you. Check the **version history** note above for details.
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/217095) in GitLab 13.6.
 
 Email notifications are sent to the participants when comments are made on a design.
 
@@ -230,25 +223,6 @@ The participants are:
 - Authors of comments on the design.
 - Anyone that is `@mentioned` in a comment on the design.
 
-### Enable or disable design email notifications **(CORE ONLY)**
-
-The design email notifications feature is under development and not ready for production use. It is
-deployed behind a feature flag that is **disabled by default**.
-[GitLab administrators with access to the GitLab Rails console](../../administration/feature_flags.md)
-can enable it.
-
-To enable it:
-
-```ruby
-Feature.enable(:design_management_design_notification_participants)
-```
-
-To disable it:
-
-```ruby
-Feature.disable(:design_management_design_notification_participants)
-```
-
 ## Filtering email
 
 Notification email messages include GitLab-specific headers. You can filter the notification emails based on the content of these headers to better manage your notifications. For example, you could filter all emails for a specific project where you are being assigned either a merge request or issue.

spec/models/design_management/design_spec.rb

@@ -375,14 +375,6 @@ RSpec.describe DesignManagement::Design do
       end
 
       it { is_expected.to contain_exactly(version_author, note_author, mentioned_user) }
-
-      context 'when the feature flag is disabled' do
-        before do
-          stub_feature_flags(design_management_design_notification_participants: false)
-        end
-
-        it { is_expected.to be_empty }
-      end
     end
   end
 

spec/services/notification_service_spec.rb

@@ -867,23 +867,6 @@ RSpec.describe NotificationService, :mailer do
           should_not_email(non_member_and_mentioned)
           should_not_email(note.author)
         end
-
-        context 'when the feature flag is disabled' do
-          before do
-            stub_feature_flags(design_management_design_notification_participants: false)
-          end
-
-          it 'sends a new note notification only to the mentioned member', :aggregate_failures do
-            notification.new_note(note)
-
-            should_email(member_and_mentioned)
-            should_not_email(design.authors.first)
-            should_not_email(member_and_author_of_second_note)
-            should_not_email(member_and_not_mentioned)
-            should_not_email(non_member_and_mentioned)
-            should_not_email(note.author)
-          end
-        end
       end
 
       context 'design management is disabled' do