testing: Use renamed systemd unit

While the alias is available after enabling the unit, we don't
actually do that in our testing environment (adding a symlink manually
would work too, then again, why not just use the proper name?).

testing/tests/tnc/tnccs-20-fail-resp/posttest.dat

@@ -1,4 +1,4 @@
-carol::systemctl stop strongswan-swanctl
-moon::systemctl stop strongswan-swanctl
+carol::systemctl stop strongswan
+moon::systemctl stop strongswan
 moon::iptables-restore < /etc/iptables.flush
 carol::iptables-restore < /etc/iptables.flush

testing/tests/tnc/tnccs-20-fail-resp/pretest.dat

@@ -4,8 +4,8 @@ moon::cat /etc/tnc_config
 carol::cat /etc/tnc_config
 carol::rm /etc/swanctl/rsa/*
 carol::rm /etc/swanctl/x509/*
-moon::systemctl start strongswan-swanctl
-carol::systemctl start strongswan-swanctl
+moon::systemctl start strongswan
+carol::systemctl start strongswan
 moon::expect-connection rw-allow
 moon::expect-connection rw-isolate
 carol::expect-connection home