Exported ghost user is mapped to the user that triggers the import

Summary

Exported ghost user is mapped to the user that triggers the import

Steps to reproduce

1. Start with a project with a merge request authored by a Ghost user (user that has been deleted).
2. Export the project
3. Import the project

The ghost user mentioned in the MR is mapped to the user that has triggered the import project.

Example Project

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What is the current bug behavior?

Exported ghost user is mapped to the user that triggers the import.

What is the expected correct behavior?

Exported ghost user is mapped to a ghost user.

Relevant logs and/or screenshots

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Output of checks

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Results of GitLab environment info

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Results of GitLab application Check

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Possible fixes

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