Remove obsolete NGINX directives to use http2_max_field_size defaults.

Closes #317.

roles/nginx/templates/nginx.conf.j2

@@ -80,8 +80,6 @@ http {
     brotli on;
     brotli_types text/plain text/css application/javascript application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;
 
-    http2_max_field_size 8k;
-
     server_tokens off;
 
     index index.php index.html index.htm;