infra_driver will be automatically figured out
in the VNF instantiation based on target VIM type
mgmt_driver is specified in the TOSCA template
per-VDU and the value the client API is ignored
Both these attributes will be removed in Ocata.
Change-Id: Ic59d7f8af6e4b1a27f4125f57d8165dc1011ce9e
Closes-bug: #1524243