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

[patilsuraj767]

Copy of issue from airshipctl. Same applies to treasuremap. - airshipit/airshipctl#648

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.

[mattmceuen]

Marking this as "design needed" because we need to have the conversation around whether we keep treasuremap, and if so how it'll fit into things. This will occur at the PTG in a couple weeks; let's hold on this one for now @patilsuraj767

[patilsuraj767]

Ok, Thanks @mattmceuen