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/route-based/rw-shared-vti/pretest.dat

@@ -7,9 +7,9 @@ moon::ip link set vti0 up
 moon::ip route add 10.3.0.0/28 dev vti0
 moon::iptables -A FORWARD -i vti0 -j ACCEPT
 moon::iptables -A FORWARD -o vti0 -j ACCEPT
-moon::systemctl start strongswan-swanctl
-carol::systemctl start strongswan-swanctl
-dave::systemctl start strongswan-swanctl
+moon::systemctl start strongswan
+carol::systemctl start strongswan
+dave::systemctl start strongswan
 moon::expect-connection rw
 carol::expect-connection home
 carol::swanctl --initiate --child home