Move EE changes from Boards::BaseService to its own module

app/services/boards/base_service.rb

 module Boards
   class BaseService < ::BaseService
+    prepend EE::Boards::BaseService
+
     # Parent can either a group or a project
     attr_accessor :parent, :current_user, :params
 
     def initialize(parent, user, params = {})
       @parent, @current_user, @params = parent, user, params.dup
     end
-
-    def set_assignee
-      assignee = User.find_by(id: params.delete(:assignee_id))
-      params.merge!(assignee: assignee)
-    end
-
-    def set_milestone
-      milestone_id = params[:milestone_id]
-
-      return unless milestone_id
-
-      return if [::Milestone::None.id,
-                 ::Milestone::Upcoming.id,
-                 ::Milestone::Started.id].include?(milestone_id)
-
-      finder_params =
-        case parent
-        when Group
-          { group_ids: [parent.id] }
-        when Project
-          { project_ids: [parent.id], group_ids: [parent.group&.id] }
-        end
-
-      milestone = MilestonesFinder.new(finder_params).find_by(id: milestone_id)
-
-      params[:milestone_id] = milestone&.id
-    end
   end
 end

ee/app/services/ee/boards/base_service.rb

+module EE
+  module Boards
+    module BaseService
+      def set_assignee
+        assignee = ::User.find_by(id: params.delete(:assignee_id))
+        params.merge!(assignee: assignee)
+      end
+
+      def set_milestone
+        milestone_id = params[:milestone_id]
+
+        return unless milestone_id
+
+        return if [::Milestone::None.id,
+                   ::Milestone::Upcoming.id,
+                   ::Milestone::Started.id].include?(milestone_id)
+
+        finder_params =
+          case parent
+          when Group
+            { group_ids: [parent.id] }
+          when Project
+            { project_ids: [parent.id], group_ids: [parent.group&.id] }
+          end
+
+        milestone = ::MilestonesFinder.new(finder_params).find_by(id: milestone_id)
+
+        params[:milestone_id] = milestone&.id
+      end
+    end
+  end
+end