Remove the temporary patch for "listing commits failed" error

What does this MR do and why?

Contributes to #452488 (closed)

Problem

gitaly!6590 (merged) introduced a bug that was raising a listing commits error if the repository was empty.

I fixed it by adding an error handler for this error: Fix 500 error in Commits API when the repositor... (!148405 - merged)

Solution

This original bug was fixed on Gitaly side: gitaly!6801 (merged). The Rails patch is not necessary anymore.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

How to set up and validate locally

1. Create a project with an empty repository (without README.md)
2. Visit http://127.0.0.1:3000/api/v4/projects/<project_id>/repository/commits
3. You should see an empty array response instead of an internal error.