database configuration only via PG* env variables and MQTT password only via configured env var

src/udi/handlers/ttn/ttn.go

@@ -81,7 +81,7 @@ func NewTTNHandler(config config.HandlerConfigT) handler.Handler {
     id: idSeq,
   }
   idSeq += 1
-  t.dbh = database.NewDatabaseHandle(config.DatabaseConnStr)
+  t.dbh = database.NewDatabaseHandle()
   return t
 }