Add MembersPreloader to fix ActiveRecord cop

MembersPresentation was previously preloading records and we wanted to
extend this in
https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/5807

By moving this to MembersPreloader we avoid introducing a new cop
exception that would otherwise have been needed
in EE::MembersPresentation

app/controllers/concerns/members_presentation.rb

@@ -12,12 +12,7 @@ module MembersPresentation
     ).fabricate!
   end
 
-  # rubocop: disable CodeReuse/ActiveRecord
   def preload_associations(members)
-    ActiveRecord::Associations::Preloader.new.preload(members, :user)
-    ActiveRecord::Associations::Preloader.new.preload(members, :source)
-    ActiveRecord::Associations::Preloader.new.preload(members.map(&:user), :status)
-    ActiveRecord::Associations::Preloader.new.preload(members.map(&:user), :u2f_registrations)
+    MembersPreloader.new(members).preload_all
   end
-  # rubocop: enable CodeReuse/ActiveRecord
 end

app/models/members_preloader.rb

+# frozen_string_literal: true
+
+class MembersPreloader
+  attr_reader :members
+
+  def initialize(members)
+    @members = members
+  end
+
+  def preload_all
+    ActiveRecord::Associations::Preloader.new.preload(members, :user)
+    ActiveRecord::Associations::Preloader.new.preload(members, :source)
+    ActiveRecord::Associations::Preloader.new.preload(members.map(&:user), :status)
+    ActiveRecord::Associations::Preloader.new.preload(members.map(&:user), :u2f_registrations)
+  end
+end