Adapt to changes from the Bifrost Victoria release

The critical part of this commit is adapting code that was still
sourcing env-vars. This file was removed from Bifrost in the Victoria
release, breaking the `kayobe seed deployment image build` command.

The other changes are not yet breaking Kayobe:

1) Release notes claim that OpenStackClient is no longer installed when
   keystone is not enabled, but it appears to still be available. Use
   the ironic native baremetal command instead except in playbooks
   related to baremetal compute nodes (i.e. overcloud ironic).

2) The use of OS_CLOUD=bifrost-inspector is deprecated and should be
   replaced by OS_CLOUD=bifrost.

Change-Id: I25078e69acdf41a4ef9957f99fe5047de54b778d
Story: 2008558
Task: 41696