core/device: ignore DEVICE_FOUND_UDEV bit on switching root

core/device: ignore DEVICE_FOUND_UDEV bit on switching root

The issue #12953 is caused by the following:
On switching root,
- deserialized_found == DEVICE_FOUND_UDEV | DEVICE_FOUND_MOUNT,
- deserialized_state == DEVICE_PLUGGED,
- enumerated_found == DEVICE_FOUND_MOUNT,
On switching root, most devices are not found by the enumeration process.
Hence, the device state is set to plugged by device_coldplug(), and then
changed to the dead state in device_catchup(). So the corresponding
mount point is unmounted. Later when the device is processed by udevd, it
will be changed to plugged state again.

The issue #23208 is caused by the fact that generated udev database in
initramfs and the main system are often different.

So, the two issues have the same root; we should not honor
DEVICE_FOUND_UDEV bit in the deserialized_found on switching root.

This partially reverts c6e892bc0eebe1d42c282bd2d8bae149fbeba85f.

Fixes #12953 and #23208.
Replaces #23215.

Co-authored-by: Martin Wilck <mwilck@suse.com>