Moved "Graphics Backend Multitreading" item to Graphics API & Optimization section

The item is currently in the section with such settings as anti-aliasing, anisotropic filtering, scaling filtering, aspect ratio, which does not fit with logic. The listed functions simply change the picture for the better or worse without obvious effects on the game itself, while "graphics backend multi-thread" directly affects the stability of the graphics (texture flickering) and the launch and playback of the game in general.

It is logical to include this item in the Graphics API & Optimization section, where it is clearly implied that changing this function can greatly affect the stability of the graphics and the game