chore: Update puma config as per recommendations (#3640)

Ability to configure workers for puma

ref:
https://devcenter.heroku.com/articles/concurrency-and-database-connections#threaded-servers
https://www.speedshop.co/2017/10/12/appserver.html

config/puma.rb

@@ -25,14 +25,14 @@ pidfile ENV.fetch('PIDFILE') { 'tmp/pids/server.pid' }
 # Workers do not work on JRuby or Windows (both of which do not support
 # processes).
 #
-# workers ENV.fetch("WEB_CONCURRENCY") { 2 }
+workers ENV.fetch('WEB_CONCURRENCY', 1)
 
 # Use the `preload_app!` method when specifying a `workers` number.
 # This directive tells Puma to first boot the application and load code
 # before forking the application. This takes advantage of Copy On Write
 # process behavior so workers use less memory.
 #
-# preload_app!
+preload_app!
 
 # Allow puma to be restarted by `rails restart` command.
 plugin :tmp_restart