DEV: Remove unused lines (#28940)

We don't support puma at all

config/nginx.sample.conf

@@ -23,13 +23,6 @@ proxy_buffers 4 32k;
 # Discourse itself tries to minimise cookie size, but we cannot control other cookies set by other tools on the same domain.
 large_client_header_buffers 4 32k;
 
-# If you are going to use Puma, use these:
-#
-# upstream discourse {
-#   server unix:/var/www/discourse/tmp/sockets/puma.sock;
-# }
-
-
 # attempt to preserve the proto, must be in http context
 map $http_x_forwarded_proto $thescheme {
   default $scheme;