Remove recursive_approach_for_all_projects FF

After a successful enabling of the recursive_approach_for_all_projects
feature flag in production, the feature flag can be removed from the
code.

app/models/namespace.rb

@@ -259,12 +259,8 @@ class Namespace < ApplicationRecord
   # Includes projects from this namespace and projects from all subgroups
   # that belongs to this namespace
   def all_projects
-    if Feature.enabled?(:recursive_approach_for_all_projects)
-      namespace = user? ? self : self_and_descendants
-      Project.where(namespace: namespace)
-    else
-      Project.inside_path(full_path)
-    end
+    namespace = user? ? self : self_and_descendants
+    Project.where(namespace: namespace)
   end
 
   # Includes pipelines from this namespace and pipelines from all subgroups

changelogs/unreleased/263442_remove_recursive_approach_for_all_projects_feature_flag.yml

+---
+title: Use recursive approach to query all projects for a namespace
+merge_request: 55043
+author:
+type: performance

config/feature_flags/development/recursive_approach_for_all_projects.yml

----
-name: recursive_approach_for_all_projects
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/44740
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/263442
-milestone: '13.5'
-type: development
-group: group::fulfillment
-default_enabled: false

spec/models/namespace_spec.rb

@@ -833,7 +833,7 @@ RSpec.describe Namespace do
   end
 
   describe '#all_projects' do
-    shared_examples 'all projects for a group' do
+    context 'when namespace is a group' do
       let(:namespace) { create(:group) }
       let(:child) { create(:group, parent: namespace) }
       let!(:project1) { create(:project_empty_repo, namespace: namespace) }
@@ -841,49 +841,25 @@ RSpec.describe Namespace do
 
       it { expect(namespace.all_projects.to_a).to match_array([project2, project1]) }
       it { expect(child.all_projects.to_a).to match_array([project2]) }
+
+      it 'queries for the namespace and its descendants' do
+        expect(Project).to receive(:where).with(namespace: [namespace, child])
+
+        namespace.all_projects
+      end
     end
 
-    shared_examples 'all projects for personal namespace' do
+    context 'when namespace is a user namespace' do
       let_it_be(:user) { create(:user) }
       let_it_be(:user_namespace) { create(:namespace, owner: user) }
       let_it_be(:project) { create(:project, namespace: user_namespace) }
 
       it { expect(user_namespace.all_projects.to_a).to match_array([project]) }
-    end
-
-    context 'with recursive approach' do
-      context 'when namespace is a group' do
-        include_examples 'all projects for a group'
-
-        it 'queries for the namespace and its descendants' do
-          expect(Project).to receive(:where).with(namespace: [namespace, child])
-
-          namespace.all_projects
-        end
-      end
-
-      context 'when namespace is a user namespace' do
-        include_examples 'all projects for personal namespace'
 
-        it 'only queries for the namespace itself' do
-          expect(Project).to receive(:where).with(namespace: user_namespace)
-
-          user_namespace.all_projects
-        end
-      end
-    end
-
-    context 'with route path wildcard approach' do
-      before do
-        stub_feature_flags(recursive_approach_for_all_projects: false)
-      end
-
-      context 'when namespace is a group' do
-        include_examples 'all projects for a group'
-      end
+      it 'only queries for the namespace itself' do
+        expect(Project).to receive(:where).with(namespace: user_namespace)
 
-      context 'when namespace is a user namespace' do
-        include_examples 'all projects for personal namespace'
+        user_namespace.all_projects
       end
     end
   end