Since Pike, minor updates are done via the composable services
framework. The old shell script approach hasn't been used/tested for 2
releases now, and should be dropped.
Also drop the UpdateWorkflow interface. Before we started doing
upgrades via Ansible, we used this pluggable resource interface to
perform oneshot operations like migrations to WSGI or AODH
services. Nowadays this interface is not referenced from anywhere and
we'd probably rather do similar operations via Ansible tasks.
Change-Id: I6c5eafe76eb53bc38d100a9ba132dd8fe6dd2d5f
a782462a1a