Fix isolated test failure

`Member` has `has_one :organization, through: :member_detail`, so
`@member.organization = @organization` requires `MemberDetail` class.

https://buildkite.com/rails/rails/builds/77274#c34f12f3-44c2-4ba9-ba44-dd4b2062a506/1158-1166

Author: kamipo

activerecord/test/cases/associations/has_one_through_disable_joins_associations_test.rb

@@ -2,6 +2,7 @@
 
 require "cases/helper"
 require "models/member"
+require "models/member_detail"
 require "models/organization"
 
 class HasOneThroughDisableJoinsAssociationsTest < ActiveRecord::TestCase