Remove unused `JoinKeys`
Remove unused `JoinKeys`

Follow up to fc0090b300defb53fb53e2b030e034cb0fb89b8a.

rafaelfranca/omg-rails,repinel/rails,MSP-Greg/rails,schuetzm/rails,bogdanvlviv/rails,lcreid/rails,bogdanvlviv/rails,esparta/rails,tgxworld/rails,kmcphillips/rails,Stellenticket/rails,schuetzm/rails,kmcphillips/rails,yawboakye/rails,vipulnsward/rails,georgeclaghorn/rails,yalab/rails,rails/rails,joonyou/rails,vipulnsward/rails,EmmaB/rails-1,tjschuck/rails,yawboakye/rails,BlakeWilliams/rails,starknx/rails,rafaelfranca/omg-rails,Vasfed/rails,yahonda/rails,joonyou/rails,yalab/rails,betesh/rails,kmcphillips/rails,tjschuck/rails,MSP-Greg/rails,eileencodes/rails,tgxworld/rails,yalab/rails,yawboakye/rails,BlakeWilliams/rails,rails/rails,yawboakye/rails,Edouard-chin/rails,tjschuck/rails,Erol/rails,kddeisz/rails,repinel/rails,Stellenticket/rails,lcreid/rails,repinel/rails,starknx/rails,Envek/rails,lcreid/rails,tgxworld/rails,MSP-Greg/rails,EmmaB/rails-1,Envek/rails,BlakeWilliams/rails,starknx/rails,eileencodes/rails,Erol/rails,yahonda/rails,joonyou/rails,esparta/rails,vipulnsward/rails,Stellenticket/rails,kddeisz/rails,repinel/rails,betesh/rails,Vasfed/rails,yahonda/rails,Envek/rails,rafaelfranca/omg-rails,kddeisz/rails,betesh/rails,georgeclaghorn/rails,Erol/rails,Edouard-chin/rails,schuetzm/rails,georgeclaghorn/rails,georgeclaghorn/rails,Vasfed/rails,tjschuck/rails,joonyou/rails,esparta/rails,eileencodes/rails,MSP-Greg/rails,schuetzm/rails,BlakeWilliams/rails,esparta/rails,bogdanvlviv/rails,Edouard-chin/rails,Envek/rails,EmmaB/rails-1,rails/rails,betesh/rails,bogdanvlviv/rails,Erol/rails,eileencodes/rails,yalab/rails,Vasfed/rails,Edouard-chin/rails,rails/rails,tgxworld/rails,vipulnsward/rails,lcreid/rails,Stellenticket/rails,kddeisz/rails,yahonda/rails,kmcphillips/rails