Remove unneeded call to fetch network info on shutdown

There is no reason to fetch the network_info from the network api on shutdown
since we can just pull it out of the local cache. There are probably other
places where this call to the network api call can be removed but this patch
just handles the case for shutdown.

Note: the following test was removed 'test_terminate_no_fixed_ips' as
the call to the network api is no longer done so this test would be the
same as test_terminate_no_network.

Closes-bug: #1288392

Change-Id: Ifbf751739c215e566926719f481c03e2c064163a
(cherry picked from commit c47900064f2f3b4384cfa3fd6fe21f452514fa36)
Merge "Remove unneeded call to fetch network info on shutdown" into stable/icehouse