DEV: Add env var to disable ActiveRecord logging in development (#10979)

If RAILS_DISABLE_ACTIVERECORD_LOGS=1 is passed when starting Rails, none of the query log output will show. This is very useful for debugging with breakpoints because logs are not flooding in constantly.

config/environments/development.rb

@@ -93,6 +93,10 @@ Discourse::Application.configure do
       end
     end
 
+    if ENV["RAILS_DISABLE_ACTIVERECORD_LOGS"] == "1"
+      ActiveRecord::Base.logger = nil
+    end
+
     if ENV['BULLET']
       Bullet.enable = true
       Bullet.rails_logger = true