Add auto_disk_config field to InstancePayload based on
instance.auto_disk_config boolean value. If true, set it to
AUTO else MANUAL.
Implements: bp additional-notification-fields-for-searchlight
Change-Id: I18af99479562e2fe5e74e6e1252b804b074fee58
This ensures that instance.availability_zone reflects what AZ the
instance is actually in. In the case where no AZ was requested at
boot, previously this would always be some default value, which
isn't as useful to the things that need to consider what AZ the
instance is actually in (without doing all the aggregate math to
determine it on the fly).
Related to blueprint cells-aware-api
Change-Id: I8d426f2635232ffc4b510548a905794ca88d7f99