nginx: use dedicated syslog-ng setup for error logs too

The error log is fairly quiet during regular use but can end up logging
one or more lines per request during DDoS attacks. For example, errors
are logged for worker_connections depletion and limit_conn rejections.
There's also currently an nginx bug with modern TLS and OpenSSL causing
some client side TLS errors to be logged as crit instead of info.

Author: thestinger

nginx/nginx.conf

@@ -1,7 +1,7 @@
 load_module modules/ngx_http_brotli_filter_module.so;
 load_module modules/ngx_http_brotli_static_module.so;
 
-error_log syslog:server=unix:/dev/log,nohostname;
+error_log syslog:server=unix:/run/nginx-error-log,nohostname;
 # leave stderr open but minimize duplicate logging to it
 error_log stderr emerg;