build-gate playbook does not evaluate MACs and bootMode properly.

[patilsuraj767]

Describe the bug
In airship-airshipctl-build-gate.yml - here we only consider hosts in ephemeral/controlplane and not from target/controlplane.
Also, get-vm-config.yaml will fail at this point - here when we will specify more than one host in ephemeral/controlplane because it will every time override target_vm_cfg ansible fact instead of appending to it.

Steps To Reproduce
Try to create kubernetes cluster with 3 controlplane by adding more nodes in target/controlplane/hostgenerator.
10_build_gate.sh fails to create the VMs with proper configuration.

Expected behavior
libvirt VMs should get created with specified configuration.

[patilsuraj767]

Please assign this issue to me.

[mattmceuen]

This relates to an issue that @ian-howell is planning to create to make AIAP able to use a non-default, multi-node infra build container; that one would have a dependency on this one. So I think this is a good one to try to tackle soon and ensure the playbooks are agnostic to the number of nodes that are use in a test setup.

[patilsuraj767]

I have patch-set ready for this. - https://review.opendev.org/c/airship/airshipctl/+/812100