Version author gets overwritten with wrong uid

[JammingBen]

Steps to reproduce

1. Set file_storage.save_version_author to true
2. Create a file "test.txt" as admin user
3. Share the file with "user01"
4. As "user01", edit this file -> The current author is "user01", the author of the first version is "admin" -> all good!
5. As "user01", roll back the first version -> current author is "admin" (good!), however, the author of the first version is now "admin" as well (bad!)

Expected behaviour

The version author should be "user01"

[JammingBen]

Another error which goes in a similar direction:

• Set file_storage.save_version_author to false
• Create a file "test.txt" as admin user
• As "admin", create a new version of this file
• As "admin", share the file with "user01"
• Set file_storage.save_version_author to true
• As "user01", create a new version of this file
• As "user01", restore a previous version -> The current version will be moved to the version list, including "user01" as author -> good!
• As "user01", roll back the version with "user01" as author again -> the current version (that has no author) will be moved to the version list -> "user01" is displayed as author for this version -> bad!

[JammingBen]

Fixed via #39673