Retina mode does not report the native display resolution to a virtual machine

**Describe the issue**

I'm running my M3 Air (native res: 2560x1664) at a display resolution of 1710x1112.

When I install `spice-vdagent`, fullscreen the VM, and run `xrandr --output Virtual-1 --auto`, `xrandr` reports a resolution of 1710x1069.

If I check the "retina" checkbox and perform the same actions, I get a resolution of exactly 2x, or 3420x2138.

Neither of these are the native resolution of my M3 Air.

This impacts integer scaling: it seems as though UTM is operating on the fake, 1710x1112 resolution when performing integer scaling, as it results in uneven pixelation at 1280x768, which should be nearest-neighbor upscaled cleanly (2x) to a width of 2560.

**Configuration**
* UTM Version: 4.5.3 (99)
* macOS Version: 14.6.1
* Mac Chip (Intel, M1, ...): M3 Air