Turn on active record cache_versioning (#1149)

This keeps the version seperate from Rails standard cache_key, which
allows for better recycling of cached entries as things get updated
freqently.  This shouldn't impact our app right now, as we are only
using our own manual cache keys for analytics.

For more details on how recyclable cache keys work, see:

* rails/rails#29092
* https://dzone.com/articles/cache-invalidation-complexity-rails-52-and-dalli-c

config/initializers/new_framework_defaults_5_2.rb

@@ -8,7 +8,7 @@
 
 # Make Active Record use stable #cache_key alongside new #cache_version method.
 # This is needed for recyclable cache keys.
-# Rails.application.config.active_record.cache_versioning = true
+Rails.application.config.active_record.cache_versioning = true
 
 # Use AES-256-GCM authenticated encryption for encrypted cookies.
 # Also, embed cookie expiry in signed or encrypted cookies for increased security.