feat: move Slack config to installation settings (#11548)

- enable Slack Configuration via InstallationConfig
- list Slack integration in super admin settings

spec/controllers/devise/omniauth_callbacks_controller_spec.rb

@@ -23,6 +23,10 @@ RSpec.describe 'DeviseOverrides::OmniauthCallbacksController', type: :request do
   end
 
   describe '#omniauth_sucess' do
+    before do
+      GlobalConfig.clear_cache
+    end
+
     it 'allows signup' do
       with_modified_env ENABLE_ACCOUNT_SIGNUP: 'true', FRONTEND_URL: 'http://www.example.com' do
         set_omniauth_config('test_not_preset@example.com')

spec/enterprise/services/enterprise/clearbit_lookup_service_spec.rb

@@ -49,6 +49,10 @@ RSpec.describe Enterprise::ClearbitLookupService do
     end
 
     context 'when Clearbit is not enabled' do
+      before do
+        GlobalConfig.clear_cache
+      end
+
       it 'returns nil without making an API call' do
         with_modified_env CLEARBIT_API_KEY: nil do
           expect(Net::HTTP).not_to receive(:start)

spec/services/conversations/message_window_service_spec.rb

@@ -56,6 +56,7 @@ RSpec.describe Conversations::MessageWindowService do
   describe 'on Facebook channels' do
     before do
       stub_request(:post, /graph.facebook.com/)
+      GlobalConfig.clear_cache
     end
 
     let!(:facebook_channel) { create(:channel_facebook_page) }