Remove devops_adoption_feature flag

This commit remove thes devops_adoption_feature feature flag.
The flag was defaulted to true in 13.7 and is now being
removed in 13.8.

app/views/admin/dev_ops_report/show.html.haml

@@ -3,7 +3,7 @@
 
 .container
   .gl-mt-3
-    - if Gitlab.ee? && Feature.enabled?(:devops_adoption_feature, default_enabled: true) && License.feature_available?(:devops_adoption)
+    - if Gitlab.ee? && License.feature_available?(:devops_adoption)
       = render_if_exists 'admin/dev_ops_report/devops_tabs'
     - else
       = render 'report'

config/feature_flags/development/devops_adoption_feature.yml

----
-name: devops_adoption_feature
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/46005
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/271568
-milestone: '13.6'
-type: development
-group: group::analytics
-default_enabled: true

doc/user/admin_area/analytics/dev_ops_report.md

@@ -59,21 +59,3 @@ DevOps Adoption allows you to:
 - Find the groups that have adopted certain features and can provide guidance to other groups on how to use those features.
 
 ![DevOps Report](img/dev_ops_adoption_v13_7.png)
-
-### Disable or enable DevOps Adoption
-
-DevOps Adoption 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.
-
-To disable it:
-
-```ruby
-Feature.disable(:devops_adoption_feature)
-```
-
-To enable it:
-
-```ruby
-Feature.enable(:devops_adoption_feature)
-```

ee/spec/features/admin/admin_dev_ops_report_spec.rb

@@ -13,19 +13,7 @@ RSpec.describe 'DevOps Report page', :js do
     gitlab_enable_admin_mode_sign_in(admin)
   end
 
-  context 'with devops_adoption_feature feature flag disabled' do
-    before do
-      stub_feature_flags(devops_adoption_feature: false)
-    end
-
-    it 'does not show the tabbed layout' do
-      visit admin_dev_ops_report_path
-
-      expect(page).not_to have_selector tabs_selector
-    end
-  end
-
-  context 'with ultimate license and devops_adoption_feature feature flag enabled' do
+  context 'with ultimate license' do
     before do
       stub_licensed_features(devops_adoption: true)
     end
@@ -117,7 +105,7 @@ RSpec.describe 'DevOps Report page', :js do
     end
   end
 
-  context 'without ultimate license and devops_adoption_feature feature flag enabled' do
+  context 'without ultimate license' do
     before do
       stub_licensed_features(devops_adoption: false)
     end