Two things are updated here:
1. The SHUTOFF status from the API is for any stopped server,
regardless of whether or not it was stopped via the REST API
or the sync_instance_power_state periodic task in the compute.
2. Remove the mention of the "shutdown_terminate" flag since that
was only ever implemented in the legacy v2 API for EC2
compatibility and it wouldn't actually work now with the v2.1
server create schema anyway.
Change-Id: I97071be164d15298fa2a5a7374a8ba8235d188e4
Related-Bug: #1722403