New Service Desk feature breaks previous ability to email issues to a repo issue tracker.

Summary

In testing for #2281, I tried sending an email using the old method where there is a unique key at the end of the email address, which can be found at the bottom of every Issue Tracker, with a URL called "Email a new issue to this project". I sent a new email to this address, and these are being bounced back to me.

Steps to reproduce

1. Open Email a new issue to this project
2. Copy email address
3. Send an email to that address

What is the current bug behavior?

Receive an email back with the following body text:

Unfortunately, your email message to GitLab could not be processed.

We couldn't find the project. Please check if there's any typo.

What is the expected correct behavior?

Email should create a new issue.