Reintroduce the feature flag for superseding code owner rule

Merge Request: gitlab.com/gitlab-org/gitlab/-/merge_requests/47897
Rollout Issue: gitlab.com/gitlab-org/gitlab/-/issues/262019

config/feature_flags/development/push_rules_supersede_code_owners.yml

+---
+name: push_rules_supersede_code_owners
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/44126
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/262019
+type: development
+group: group::source code
+default_enabled: true

ee/lib/ee/gitlab/checks/diff_check.rb

@@ -20,7 +20,8 @@ module EE
         end
 
         def validate_code_owners?
-          return false if updated_from_web? || user_access.can_push_to_branch?(branch_name)
+          return false if updated_from_web?
+          return false if ::Feature.enabled?(:push_rules_supersede_code_owners, project, default_enabled: true) && user_access.can_push_to_branch?(branch_name)
 
           project.branch_requires_code_owner_approval?(branch_name)
         end

ee/spec/lib/gitlab/checks/diff_check_spec.rb

@@ -60,6 +60,18 @@ RSpec.describe Gitlab::Checks::DiffCheck do
         it 'returns false' do
           expect(validate_code_owners).to eq(false)
         end
+
+        context 'when push_rules_supersede_code_owners is disabled' do
+          before do
+            stub_feature_flags(push_rules_supersede_code_owners: false)
+          end
+
+          it 'returns branch_requires_code_owner_approval?' do
+            expect(project).to receive(:branch_requires_code_owner_approval?).and_return(true)
+
+            expect(validate_code_owners).to eq(true)
+          end
+        end
       end
     end