Support using volume-backed instances for building

[m-bull]

No description provided.

CI failed

[sjpb]

Testing fat image build here: https://github.com/stackhpc/ansible-slurm-appliance/actions/runs/4892239063

Note this needs to pass before merging this PR, but the appliance does NOT need to be updated to use the result of this fatimage build (and in fact that image should be deleted once built).

Edit: fat image build completed OK.

[sjpb]

Deploy CI failed on:

2023-05-05T09:52:04.5929957Z TASK [cloudalchemy.grafana : Enable and start Grafana systemd unit] ************
2023-05-05T09:53:36.0726174Z �[0;31mfatal: [ci4892004543-control]: FAILED! => {�[0m
2023-05-05T09:53:36.0728396Z �[0;31m    "changed": false�[0m
2023-05-05T09:53:36.0729041Z �[0;31m}�[0m
2023-05-05T09:53:36.0729626Z �[0;31m�[0m
2023-05-05T09:53:36.0730208Z �[0;31mMSG:�[0m
2023-05-05T09:53:36.0730776Z �[0;31m�[0m
2023-05-05T09:53:36.0731788Z �[0;31mUnable to start service grafana-server: Job for grafana-server.service failed because a timeout was exceeded.�[0m
2023-05-05T09:53:36.0735842Z �[0;31mSee "systemctl status grafana-server.service" and "journalctl -xe" for details.�[0m
2023-05-05T09:53:36.0736703Z �[0;31m�[0m

Going to rerun it.