Change logic for return 404

To avoid a failing spec and repeating the `not_found`
before_action which causes issues.

app/controllers/admin/integrations_controller.rb

@@ -5,11 +5,12 @@ class Admin::IntegrationsController < Admin::ApplicationController
   include IntegrationsHelper
 
   before_action :not_found, unless: -> { instance_level_integrations? }
-  before_action :not_found, unless: -> { instance_level_integration_overrides? }, only: :overrides
 
   feature_category :integrations
 
   def overrides
+    return render_404 unless instance_level_integration_overrides?
+
     respond_to do |format|
       format.json do
         projects = Project.with_active_integration(integration.class).merge(::Integration.not_inherited)