Per-subnet vlan id parameters are already rendered in
network-environment.yaml. This change uses networks data
and roles data so that per-subnet vlan id param is used
when passing the relevant NetworkVlanId data to nic-config
templates.
By using the generic %network%NetworkVlanId (no subnet suffix)
in nic-config templates instead of %network%NetworkVlanId_%subnet%,
this allow homogeneous computes in multiple sites to use the
same nic-config template.
Also use type: number for all vlan parameters.
Closes-Bug: #1821043
Change-Id: Id8e76ae7c41a562f5c47d911c42aa18001c11be1