Add `:nested_groups` metadata to `Groups::NestedCreateService` specs

spec/services/groups/nested_create_service_spec.rb

@@ -14,14 +14,14 @@ describe Groups::NestedCreateService do
       expect(service.execute).to eq(child)
     end
 
-    it 'reuses a parent if it already existed' do
+    it 'reuses a parent if it already existed', :nested_groups do
       parent = create(:group, path: 'a-group')
       parent.add_owner(user)
 
       expect(service.execute.parent).to eq(parent)
     end
 
-    it 'creates group and subgroup in the database' do
+    it 'creates group and subgroup in the database', :nested_groups do
       service.execute
 
       parent = Group.find_by_full_path('a-group')