With "VM Clone Auto Migrate" on, a new clone was migrated to a random
compute, whatever storage, CPU or network that host had, and a failed
migration showed as a failed clone although the clone existed.
The setting and its code are removed; migration appsettings.0015
deletes the setting. A clone can be migrated afterwards like any VM.
The README's update notes list the migration changes: the migration
address, storage pools for the disk check, and this setting.
