api2/node/syslog: use 'real_service_name' here also

for now this only does the 'postfix' -> 'postfix@-' conversion,
fixes the issue that we only showed the 'postfix' service syslog
(which is rather empty in a default setup) instead of the instance one

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

src/api2/node.rs

@@ -34,7 +34,7 @@ pub mod subscription;
 pub(crate) mod rrd;
 
 mod journal;
-mod services;
+pub(crate) mod services;
 mod status;
 mod syslog;
 mod time;