strongswan: speedup prepare
The bottleneck was loading selinux module, which takes 30s for some reason. Skip this, when already loaded, so each setup except the first one takes 2s.
@RunFeatures:strongswan
@RunTests:strongswan_add_profile,strongswan_connection_renewal,strongswan_terminate,strongswan_delete_active_profile,strongswan_dns,strongswan_start_as_secondary
Closes #2 (closed)