testing: Improve runtime of TNC tests by storing the SQLite DB in ramfs

This saves about 50%-70% of the time needed for scenarios that use a DB.

testing/tests/tnc/tnccs-20-pdp-eap/posttest.dat

@@ -3,7 +3,7 @@ carol::ipsec stop
 dave::ipsec stop
 alice::ipsec stop
 alice::service apache2 stop
-alice::rm /etc/pts/config.db
+alice::umount /etc/pts
 moon::iptables-restore < /etc/iptables.flush
 carol::iptables-restore < /etc/iptables.flush
 dave::iptables-restore < /etc/iptables.flush