Randomize disk GUID of USB image during boot

All devices that the USB image is copied to have the same GUID, which can cause problems if multiple Tails devices are plugged in at the same time. The plan is to prevent this by setting a random disk GUID during the first boot of the device.

Feature Branch: segfault:feature/15292-usb-image

Parent Task: #15293 (closed)

Related issues

Related to #15681 (closed)

Original created by @segfault on 15317 (Redmine)

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