Add logging for Rails cache timeouts (#21667)

* Reduce redis cache store connect timeout from default 20 seconds to 5 seconds

* Log cache store errors

config/initializers/cache_logging.rb

@@ -0,0 +1,3 @@
+# Log cache errors with Rail's logger
+# This used to be the default in old Rails versions: https://github.com/rails/rails/commit/7fcf8590e788cef8b64cc266f75931c418902ca9#diff-f0748f0be8a653eea13369ebb1cadabcad71ede7cfaf20282447e64329817befL86
+Rails.cache.logger = Rails.logger