RO-3316 Enable container images for MNAIO tests
RO-3316 Enable container images for MNAIO tests

As discussed in [1] the container images should now
be used in build tests, rather than disabled. The
setting for the MNAIO tests was missed in [1] so
this patch resolves that.

[1] https://github.com/rcbops/rpc-openstack/pull/2797

rcbops/rpc-openstack,robb-romans/rpc-openstack,BjoernT/rpc-openstack,jacobwagner/rpc-openstack,BjoernT/rpc-openstack,cloudnull/rpc-openstack,cloudnull/rpc-openstack,jacobwagner/rpc-openstack,robb-romans/rpc-openstack,hughsaunders/rpc-openstack,rcbops/rpc-openstack,hughsaunders/rpc-openstack