Allow the email domain for project bots to be customized

Release notes

Problem to solve

We default the domain on the email address for project bots to example.com. This can lead to issues with customer's internal mail systems due to being Undeliverable. We would like the ability to set a custom domain or default it to the domain of the GitLab server.

Intended users

Proposal

Allow for the project bot to have a domain that the admin chooses other than example.com.

Further details

Permissions and Security

Documentation

https://docs.gitlab.com/ee/user/project/settings/project_access_tokens.html#project-bot-users

What does success look like, and how can we measure that?

GitLab administrators are able to customize the domain for project bot users.

Links / references

Customer ticket: https://gitlab-federal-support.zendesk.com/agent/tickets/449 (internal use)