Update some more config following Rails 8 upgrade

Here are some updates to a handful of config settings that I didn't
spend enough time looking into when I ran `rails app:update` the other
day following the upgrade to Rails 8.

`config.cache_store`:

The before and after `config.cache_store` settings are both just
different eras of Rails default config. I don't think we're invested in
the old default, so I'm accepting the new suggestion.

`config.active_record.query_log_tags_enabled`:

Enabling SQL query log tags in development doesn't sound very risky.

`config.public_file_server.enabled`:

Rails's public file server used to be off by default but that was
apparently switched to on by default in a recent Rails version. The
environment variable `RAILS_SERVE_STATIC_FILES` is something that Rails
itself introduced and I haven't found any evidence to suggest that this
app ever set the variable, so in practice the public file server was
always off. I don't see any reason to change that now.

config/environments/development.rb

@@ -20,15 +20,14 @@
   if Rails.root.join("tmp/caching-dev.txt").exist?
     config.action_controller.perform_caching = true
     config.action_controller.enable_fragment_cache_logging = true
-
-    config.cache_store = :memory_store
     config.public_file_server.headers = { "cache-control" => "public, max-age=#{2.days.to_i}" }
   else
     config.action_controller.perform_caching = false
-
-    config.cache_store = :null_store
   end
 
+  # Change to :null_store to avoid any caching.
+  config.cache_store = :memory_store
+
   # Don't care if the mailer can't send.
   config.action_mailer.raise_delivery_errors = false
 
@@ -63,7 +62,7 @@
   config.active_record.verbose_query_logs = true
 
   # Append comments with runtime information tags to SQL queries in logs.
-  # config.active_record.query_log_tags_enabled = true
+  config.active_record.query_log_tags_enabled = true
 
   # Highlight code that enqueued background job in logs.
   config.active_job.verbose_enqueue_logs = true

config/environments/production.rb

@@ -15,8 +15,8 @@
   # Turn on fragment caching in view templates.
   config.action_controller.perform_caching = true
 
-  # Disable serving static files from `public/`, relying on NGINX/Apache to do so instead.
-  config.public_file_server.enabled = ENV["RAILS_SERVE_STATIC_FILES"].present?
+  # Disable serving static files from `public/`.
+  config.public_file_server.enabled = false
 
   # Cache assets for far-future expiry since they are all digest stamped.
   # config.public_file_server.headers = { "cache-control" => "public, max-age=#{1.year.to_i}" }