Fix examples/VPC_EC2_Instance_With_Multiple_Dynamic_IPAddresses.py

It was broken since its introduction in fc88fd01c1b609c43b5fdd7faf90df99ab140634
- introduces ec2.NetworkInterfaceProperty
- adds properties to NetworkInterface:
    - SecondaryPrivateIpAddressCount
    - NetworkInterfaceId
    - DeviceIndex
- makes SubnetId not required
- adds PrivateIpAddress to EIPAssociation