If nova-api is delayed starting then the nova_wait_for_compute_service
can timeout. A deployment using a slow/busy remote container repository is
particularly susceptible to this issue. To resolve this nova_compute and
nova_wait_for_compute_service have been postponed to step_5 and a task
has been added to step_4 to ensure nova_api is active before proceeding.
Change-Id: I6fcbc5cb5d4f3cbb618d9661d2a36c868e18b3d6
Closes-bug: #1842948
8a87cbcc34