testing: Reduce runtime of all tests that use SQLite databases by storing them in ramfs

testing/tests/sql/shunt-policies-nat-rw/posttest.dat

@@ -2,7 +2,4 @@ sun::ipsec stop
 alice::ipsec stop
 venus::ipsec stop
 sun::iptables-restore < /etc/iptables.flush
-alice::rm /etc/ipsec.d/ipsec.*
-venus::rm /etc/ipsec.d/ipsec.*
-sun::rm /etc/ipsec.d/ipsec.*
 moon::iptables -t nat -F