Adds option to override commit email

What does this MR do?

In order to keep the users' email private, this MR adds the option to override the commit_email used to be displayed in the users commits with a non-existing email such as id-username@noreply.gitlab.com.

Screenshots

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has ~"Requires e2 tests" label. See the Test Planning Process.

What are the relevant issue numbers?

Closes #43521 (closed)