[2020] Optimizing rust

We've seen this and are investigating.

According to the Unity documentation, a value isn't required to enable it. Long as the command-line argument is present it should be enabled.

https://docs.unity3d.com/ScriptReference/Rendering.RenderingThreadingMode.NativeGraphicsJobsWithoutRenderThread.html

Update: We've done some brief testing internally and so far we've seen no discernible improvement to Rust's performance. It's possible this was an issue in the Unity version Escape from Tarkov is currently using but has since been fixed - We'll continue to investigate.

Escape from Tarkov is using Unity 2018.2 (I believe) and Rust is using Unity 2019.3 "scripting-runtime-version" is deprecated as of Unity 2019.1

In short, this line is no longer required and would not cause any impact on performance for Rust.