Files not tracked with LFS when uploaded through the web interface

What does this MR do and why?

This MR aims to fix a bug where uploading a file (that is LFS tracked) via the UI creates a new branch with the file but the file wasn't being stored as an LFS object, just a regular object within git.

How to set up and validate locally

Follow the steps to reproduce from the reported issue, testing against gitlab-org/gitlab master branch to see the error and then against the 326342-files-not-tracked-with-lfs-when-uploaded-through-the-web-interface-2 branch to verify the fix.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #326342 (closed)