Configuration Autorecovery: Improve Warning Messages for Broken Autosave Configurations

Bug ID 6845614: For most instances of a corrupted autosave configuration, the following misleading warning message is logged in the Logical Domains Manager log file:

warning: Autosave config 'config-name' missing HV MD

The actual reason for this message could be when a guest domain or control domain has a corrupted MD, or has no valid MD.