testing: Use absolute path to the _updown script in SQL scenarios

/usr/local/sbin is not included in PATH set by the charon init script and
since the ipsec script is obsolete when using swanctl it makes sense to
change this anyway.

testing/tests/sql/rw-psk-rsa-split/hosts/carol/etc/ipsec.d/data.sql

@@ -93,7 +93,7 @@ INSERT INTO peer_configs (
 INSERT INTO child_configs (
   name, updown
 ) VALUES (
-  'home', 'ipsec _updown iptables'
+  'home', '/usr/local/libexec/ipsec/_updown iptables'
 );
 
 INSERT INTO peer_config_child_config (