[data_release] Permission not added to unversioned files if version specified

[charlottesce]

Brief summary of changes

When adding version permissions for a user, permissions for unversioned files are no longer added

Testing instructions (if applicable)

1. Go to data_release
2. Make sure that there is at least one file uploaded without a version (version will show up as "Unversioned"), and at least one file uploaded under a specified version
3. Add permissions for a user to give them permission to the specified version
4. See that the user now only has permission to the specified version, and not "Unversioned" too

Link(s) to related issue(s)

• Resolves [data_release] "Unversioned" permissions granted with every version #8741

[driusan]

@CamilleBeau you reported the issue this is reported to fix, can you review/test?

[CamilleBeau]

Works well & code looks good to me!