Fix incorrect config argument position for builtin SSH server (#25341)

The "--config" option is a global option, it shouldn't appear at the
end.

Otherwise it might not be respected in some cases.

Caught by #25330 and use a separate PR to fix it for 1.20

modules/ssh/ssh.go

@@ -68,7 +68,7 @@ func sessionHandler(session ssh.Session) {
 
 	log.Trace("SSH: Payload: %v", command)
 
-	args := []string{"serv", "key-" + keyID, "--config=" + setting.CustomConf}
+	args := []string{"--config=" + setting.CustomConf, "serv", "key-" + keyID}
 	log.Trace("SSH: Arguments: %v", args)
 
 	ctx, cancel := context.WithCancel(session.Context())