@mention email notifications show username instead of full name

Issue Summary

Email notifications for @mention show username instead of full name for updates or issue being commented.

Steps to Reproduce

1. Configure a user with the following format:
   • Username: user
   • Full name: I Am A User
   • Email: user@example-instance.com
2. Create a new issue
3. @mention 'user' in the comment
4. View the email
5. @mention 'user' in another comment
6. Flush Mail Queue and observe the email

Expected Results

Full name is displayed in the email.

Actual Results

Username is displayed in the email.

Note

This behavior does not happen when:

• 'Batching email notifications' is enabled
• Emails are flushed from the Mail Queue

Note on a partial fix.

We are very sorry, we only partially fixed the problem in 8.22.0/8.20.6 versions, specifically - emails with updates about mentions with full names.
We missed the other part, email updates when issues are being commented which would include a mention. Team is working on it.

Workaround

Enable 'Batching email notifications' and set the interval to 2 minutes to minimize change.