Description of problem:this BZ was following https://bugzilla.redhat.com/show_bug.cgi?id=1468700
now we can Refresh Providers Inventory but we can't refresh network manager. which means we can't provision to such provider

Version-Release number of selected component (if applicable):5.7.4/5.8.2


How reproducible:100%


Steps to Reproduce:
1.have a setup which is described in https://bugzilla.redhat.com/show_bug.cgi?id=1468700 - to add empty IPv6 configuration one needs Load balancer
2.add such Azure region to CFME
3.refresh

Actual results: Azure Network Manager refresh state - Error - 1 Minute Ago
undefined method `subnet' for #<Azure::Armrest::Network::NetworkInterface::Properties::IpConfiguration::Properties:0x...


Expected results: refresh should be completed


Additional info:Provision is impossible - all dropdowns are empty