Remove the global default branch feature flag

This has been enabled by default for a number of releases now. Time for
it to go.

app/views/admin/application_settings/repository.html.haml

@@ -2,8 +2,7 @@
 - page_title _("Repository")
 - @content_class = "limit-container-width" unless fluid_layout
 
-- if Feature.enabled?(:global_default_branch_name, default_enabled: true)
-  %section.settings.as-default-branch-name.no-animate#js-default-branch-name{ class: ('expanded' if expanded_by_default?) }
+%section.settings.as-default-branch-name.no-animate#js-default-branch-name{ class: ('expanded' if expanded_by_default?) }
   .settings-header
     %h4
       = _('Default initial branch name')

changelogs/unreleased/325163-remove-global-default-branch-ff.yml

+---
+title: Remove the global default branch feature flag
+merge_request: 59024
+author:
+type: other

config/feature_flags/development/global_default_branch_name.yml

----
-name: global_default_branch_name
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/35269
-rollout_issue_url: 
-milestone: '13.2'
-type: development
-group: group::source code
-default_enabled: true

doc/user/project/repository/branches/default.md

@@ -60,7 +60,6 @@ GitLab administrators can configure a new default branch name at the
 > - It's deployed behind a feature flag, enabled by default.
 > - It cannot be enabled or disabled per-project.
 > - It's recommended for production use.
-> - For GitLab self-managed instances, GitLab administrators can opt to [disable it](#enable-or-disable-custom-initial-branch-name).
 
 GitLab [administrators](../../../permissions.md) of self-managed instances can
 customize the initial branch for projects hosted on that instance. Individual
@@ -75,25 +74,6 @@ Projects created on this instance after you change the setting use the
 custom branch name, unless a group-level or subgroup-level configuration
 overrides it.
 
-#### Enable or disable custom initial branch name **(FREE SELF)**
-
-Setting the default initial branch name 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(:global_default_branch_name)
-```
-
-To enable it:
-
-```ruby
-Feature.enable(:global_default_branch_name)
-```
-
 ### Group-level custom initial branch name **(FREE)**
 
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/221014) in GitLab 13.6.

spec/views/admin/application_settings/repository.html.haml_spec.rb

@@ -12,23 +12,6 @@ RSpec.describe 'admin/application_settings/repository.html.haml' do
   end
 
   describe 'default initial branch name' do
-    context 'when the feature flag is disabled' do
-      before do
-        stub_feature_flags(global_default_branch_name: false)
-      end
-
-      it 'does not show the setting section' do
-        render
-
-        expect(rendered).not_to have_css("#js-default-branch-name")
-      end
-    end
-
-    context 'when the feature flag is enabled' do
-      before do
-        stub_feature_flags(global_default_branch_name: true)
-      end
-
     it 'has the setting section' do
       render
 
@@ -42,5 +25,4 @@ RSpec.describe 'admin/application_settings/repository.html.haml' do
       expect(rendered).to have_content("Set the default name of the initial branch when creating new repositories through the user interface.")
     end
   end
-  end
 end