UEFI Boot is erroneously enabled for new non-x86/ARM machines, making them unusable

[kFYatek]

Describe the issue
Let me explain this by example reproduction steps:

• Create a New Virtual Machine
• Click Emulate
• Click Other
• Point to a Mac OS 9.1+ or PPC Mac OS X ISO
• Set the system architecture to PowerPC, single CPU, some reasonable RAM and disk size values
• Try to boot the machine
• Observe that the machine freezes on the spinning wheel animation for a while, before failing with message: "An internal error has occurred"

This is caused by the BootUefi property being set to true. This can be fixed by editing config.plist manually and removing the BootUefi attribute. The machine still won't boot due to invalid video and audio adapters set for the platform, but this can be fixed from the GUI.

The BootUefi option technically can be fixed from the GUI as well, but it requires changing the architecture to x86_64, disabling "UEFI Boot", and switching back to PowerPC. It shouldn't be this complicated. "UEFI Boot" on platforms for which it doesn't make sense, should be either disabled by default, or ignored.

Configuration

• UTM Version: 3.1.5 (53) installed via Homebrew
• OS Version: macOS 12.3.1
• Apple Silicon