Reuse `Boards::CreateService` for EE

We only overwrite `can_create_board?` so it allows creating multiple
boards when available.

app/controllers/ee/projects/boards_controller.rb

@@ -9,7 +9,7 @@ module EE
       end
 
       def create
-        board = EE::Boards::CreateService.new(project, current_user, board_params).execute
+        board = ::Boards::CreateService.new(project, current_user, board_params).execute
 
         respond_to do |format|
           format.json do

app/services/ee/boards/create_service.rb

 module EE
   module Boards
-    class CreateService < BaseService
-      def execute
-        return nil unless can_create_board?
-
-        board = project.boards.create(params)
-
-        if board.persisted?
-          board.lists.create(list_type: :backlog)
-          board.lists.create(list_type: :closed)
-        end
-
-        board
-      end
-
+    module CreateService
       def can_create_board?
-        project.feature_available?(:multiple_issue_boards) || project.boards.size < 1
+        raise NotImplementedError unless defined?(super)
+
+        project.feature_available?(:multiple_issue_boards) || super
       end
     end
   end

spec/services/ee/boards/create_service_spec.rb

 require 'spec_helper'
 
-describe EE::Boards::CreateService, services: true do
+describe Boards::CreateService, services: true do
   describe '#execute' do
     let(:project) { create(:empty_project) }