feat: rework logging and rotation rules

roles/nginx/templates/nginx.conf.j2

@@ -1,6 +1,10 @@
 user {{ nginx_user }};
 worker_processes {{ nginx_worker_processes }};
+{% if nginx_log_backend == 'journald' %}
+error_log syslog:server=unix:/dev/log,nohostname;
+{% else %}
 error_log /var/log/nginx/error.log;
+{% endif %}
 pid /run/nginx.pid;
 
 include /usr/share/nginx/modules/*.conf;
@@ -14,7 +18,11 @@ http {
                       '$status $body_bytes_sent "$http_referer" '
                       '"$http_user_agent" "$http_x_forwarded_for"';
 
+{% if nginx_log_backend == 'journald' %}
+    access_log syslog:server=unix:/dev/log,nohostname main;
+{% else %}
     access_log  /var/log/nginx/access.log  main;
+{% endif %}
 
     sendfile            on;
     tcp_nopush          on;