Remove sub_group_webhooks feature falg

The feature flag was introduced because there
was no limit for the number of webhooks in a group.
This raised a concern that enabling group hooks to
be triggered from a subgroup could result in a large
number of requests per action.

With https://gitlab.com/gitlab-org/gitlab/-/merge_requests/25129
we introduced a limit for webhooks on a group
and the feature flag is not needed anymore

ee/app/models/ee/project.rb

@@ -756,8 +756,6 @@ module EE
     private
 
     def group_hooks
-      return group.hooks unless ::Feature.enabled?(:sub_group_webhooks, self)
-
       GroupHook.where(group_id: group.self_and_ancestors)
     end
 

ee/changelogs/unreleased/207123-remove-sub_group_webhooks-feature-flag.yml

+---
+title: Activate triggering webhooks from a subgroup feature
+merge_request: 26070
+author:
+type: added

ee/spec/models/project_spec.rb

@@ -631,14 +631,6 @@ describe Project do
         it_behaves_like 'returns nil when the feature is not available'
 
         it { is_expected.to eq(true) }
-
-        context 'when sub_group_webhooks feature flag is disabled' do
-          before do
-            stub_feature_flags(sub_group_webhooks: false)
-          end
-
-          it { is_expected.to eq(false) }
-        end
       end
     end
   end
@@ -677,32 +669,12 @@ describe Project do
 
         it_behaves_like 'triggering group webhook'
 
-        context 'when sub_group_webhooks feature flag is disabled' do
-          before do
-            stub_feature_flags(sub_group_webhooks: false)
-          end
-
-          it_behaves_like 'triggering group webhook'
-        end
-
         context 'in sub group' do
           let(:sub_group) { create :group, parent: group }
           let(:sub_sub_group) { create :group, parent: sub_group }
           let(:project) { create(:project, namespace: sub_sub_group) }
 
           it_behaves_like 'triggering group webhook'
-
-          context 'when sub_group_webhooks feature flag is disabled' do
-            before do
-              stub_feature_flags(sub_group_webhooks: false)
-            end
-
-            it 'does not execute the hook' do
-              expect(WebHookService).not_to receive(:new).with(group_hook, { some: 'info' }, 'push_hooks')
-
-              project.execute_hooks(some: 'info')
-            end
-          end
         end
       end
     end