Fix VPN namespace name for external IP query

Use correct namespace name 'vpn' instead of 'openvpn-namespace'.

Version: v0.1.233

agent/src/collectors/systemd.rs

@@ -850,7 +850,7 @@ impl SystemdCollector {
         }
     }
 
-    /// Get VPN external IP by querying through the openvpn-namespace
+    /// Get VPN external IP by querying through the vpn namespace
     fn get_vpn_external_ip(&self) -> Option<String> {
         let output = Command::new("timeout")
             .args(&[
@@ -858,7 +858,7 @@ impl SystemdCollector {
                 "ip",
                 "netns",
                 "exec",
-                "openvpn-namespace",
+                "vpn",
                 "curl",
                 "-s",
                 "--max-time",