Fix EE load balancing crashing on Rails 5
Rails 5 added the preparable
argument to select_all
, which was added
to help prepared statement caching via
https://github.com/rails/rails/commit/2a56b2d90d4fed8548e3a1e7a7b206454858c872.
This argument is not needed by the load balancer since prepared statements are disabled, but it needs to be present or a method signature error is thrown.