Neutron accepts multiple values for availability zone hint, subnet, and
fixed-ip and return lists with multiple elements. At this moment
the corresponding properties in our resource types do not support
array value so we should always pick the first element to fill
the interface mismatch.
Change-Id: I3bcca8b7824be1c56661bef56ed523cc4dfb5d7a
(cherry picked from commit 31862093eb128c263f11926388f3eb7325c6ae80)
(cherry picked from commit 50efca8bb825ba45a72fc9d90babc7d239d1a997)