fix(app-store): simplify inbox creation controller

spec/controllers/api/v1/accounts/inboxes_controller_spec.rb

@@ -434,18 +434,6 @@ RSpec.describe 'Inboxes API', type: :request do
         expect(response.body).to include('+123456789')
       end
 
-      it 'does not create an app store inbox when the feature is disabled' do
-        post "/api/v1/accounts/#{account.id}/inboxes",
-             headers: admin.create_new_auth_token,
-             params: { name: 'App Store Reviews',
-                       channel: { type: 'app_store', app_id: '123456789', issuer_id: SecureRandom.uuid, key_id: 'KEY123',
-                                  private_key: OpenSSL::PKey::EC.generate('prime256v1').to_pem } },
-             as: :json
-
-        expect(response).to have_http_status(:forbidden)
-        expect(response.parsed_body['message']).to eq('App Store Reviews channel is not enabled for this account')
-      end
-
       it 'creates an app store inbox when the feature is enabled' do
         app_store_client = instance_double(AppStoreConnect::Client)