Code review comment for ~chad.smith/cloud-init:ubuntu/xenial

Just added the patch in git, built the deb and tested on azure that the fix doesn't remove ENI hotplug scripts, but still gets IMDS data in instance-data.json

ubuntu@SRU-worked-azure:~$ sudo python3 -c 'from cloudinit.stages import _pkl_load; print(_pkl_load("/var/lib/cloud/instance/obj.pkl").network_config)'
{'config': [{'params': {'driver': 'hv_netvsc', 'device_id': '0x3'}, 'name': 'eth0', 'type': 'physical', 'mac_address': '00:0d:3a:04:3c:ea', 'subnets': [{'type': 'dhcp'}]}], 'version': 1}

ubuntu@SRU-worked-azure:~$ cloud-init query --format '{{ds.meta_data.imds}}'{'compute': {'vmSize': 'Standard_DS1_v2', 'name': 'my-x1', 'offer': 'UbuntuServer', 'vmScaleSetName': '', 'sku': '16.04-DAILY-LTS', 'osType': 'Linux', 'location': 'eastus2', 'version': '16.04.201810160', 'tags': '', 'platformUpdateDomain': '0', 'platformFaultDomain': '0', 'zone': '', 'resourceGroupName': 'srugroup1', 'vmId': 'cb49a483-a6ce-491c-a977-20ab0d546f2b', 'publisher': 'Canonical', 'placementGroupId': '', 'subscriptionId': '12aad61c-6de4-4e53-a6c6-5aff52a83777'}, 'network': {'interface': [{'ipv4': {'subnet': [{'prefix': '24', 'address': '10.0.0.0'}], 'ipAddress': [{'publicIpAddress': '137.116.84.123', 'privateIpAddress': '10.0.0.4'}]}, 'ipv6': {'ipAddress': []}, 'macAddress': '000D3A043CEA'}]}}