Fix issue provisioning to a VM Network from a DVS

[agrare]

When provisioning a VM from a template that has a NIC on a DV Portgroup to a regular VM network the NIC backing isn't reset, just the network name is set but the rest of the dvportgroup settings are still there. This causes the new NIC to be put on the populated
portgroup port and the provision will fail.

[agrare]

cc @gmcculloug I ran in to this while testing #10 and thought I broke something but its an issue on master also 😄

[agrare]

Without this change the new spec test will fail with:

Failures:

  1) ManageIQ::Providers::Vmware::InfraManager::Provision A new provision request, VMware provisioning should replace network card backing
     Failure/Error: expect(vmcs["deviceChange"][0]["device"]["backing"].xsiType).to eq("VirtualEthernetCardNetworkBackingInfo")
     
       expected: "VirtualEthernetCardNetworkBackingInfo"
            got: "VirtualEthernetCardDistributedVirtualPortBackingInfo"
     
       (compared using ==)
     # ./spec/models/manageiq/providers/vmware/infra_manager/provision_spec.rb:93:in `block (4 levels) in <top (required)>'

because the backing wasn't actually getting reset, just the deviceName was being overwritten but everything else was the same.

[gmcculloug]

This changes the build_config_spec_vlan method to be more like build_config_spec_dvs which completely rebuilds the vdcs.device.backing structure. 👍

Are there any possible side effects to this change or should users not see any difference?

[agrare]

The only side-effect I can imagine would be expecting some property of the backing to be inherited from the template where now it is getting overwritten.

This shouldn't be an issue because the two backing types (VirtualEthernetCardDistributedVirtualPortBackingInfo and VirtualEthernetCardNetworkBackingInfo) share 0 common properties

[agrare]

@blomquisg can you review?

[agrare]

ping @blomquisg