devstack-base is changed to descend from
openstack-multinode-fips which is defined in
project-config.
This allows jobs to execute the enable_fips playbook
to enable FIPS mode on the node, but only if they
opt-in by setting enable_fips to True. Otherwise,
this is a no-op.
Change-Id: I5631281662dbd18056ffba291290ed0978ab937e