Apple backend does not support "without saving" option

**Describe the issue**
The example provided in the guide's scripting cheat sheet does not work for an Apple (VZ) backend.

```
tell application "UTM"
set vm to virtual machine named "macOS"
start vm without saving
end tell
```

If you run this simple script, you will get the error:

```
install.applescript:78:101: execution error: UTM got an error: Operation not supported by the backend. (-2700)
```

This is not expected, because in the guest support it indicates under unsupported features that save states is unsupported only "before macOS 14" but this was observed on 15.x host and guest.

See:

* https://docs.getutm.app/scripting/cheat-sheet/
* https://docs.getutm.app/guest-support/macos/

**Configuration**
* UTM Version: 4.6.5
* macOS Version: 15.6
* Mac Chip (Intel, M1, ...): M1

**Crash log**
N/A

**Debug log**
N/A

**Upload VM**
N/A