testing: Move collector.db in tnc/tnccs-20-ev-pt-tls scenario to /etc/db.d

Also move initialization to the pretest script (it's way faster in the
in-memory database).

testing/hosts/bob/etc/strongswan.conf

@@ -3,8 +3,3 @@
 charon {
   load = sha1 sha2 md5 aes des hmac pem pkcs1 x509 revocation constraints curve25519 pubkey gmp random nonce curl kernel-netlink socket-default updown stroke vici
 }
-
-sw-collector {
-  database = sqlite:///etc/pts/collector.db
-  history = /var/log/apt/history.log
-}