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/tests/tnc/tnccs-20-ev-pt-tls/hosts/carol/etc/strongswan.conf

@@ -7,7 +7,7 @@ libtls {
 libimcv {
   plugins {
     imc-swima {
-      swid_database = sqlite:///etc/pts/collector.db
+      swid_database = sqlite:///etc/db.d/collector.db
     }
   }
 }