As far as I’m aware this is currently not supported and working the way you want to do it.
A side note to this: Please note that the ticket number can’t be filled in, if you’re on a ticket creation process, so the signature will be broken for that moment.
The only way that might have worked would be inserting the URL from a clean state (so notepad, something that does not copy or wrap HTML magic around your string) and do it like this:
The result however shows, it’s not working:
Guess what, there is an option:
Trigger and Scheduler
Again, ensure to copy paste it without HTML content.
Edit: No database and console fiddling needed.
(Also, I’d never hack inside the database directly, but oh well 
)