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)
Remove unnecessary call to fetch info_cache

The _heal_instance_info cache() always accesses instance['info_cache']
therefore we should always load the info_cache so we can avoid the extra
query to fetch it.

Change-Id: I3c2e005b98abf2a80276562cc05e88ba5ff199bc
Closes-bug: #1309239
(cherry picked from commit 5aa29b6b0a34d603e882a80cdc8e936f983b1892)
remove unneeded call to network_api on rebuild_instance

When rebuilding an instance we call the network_api and which results in
calling neutron and updating the info cache. We do not actually need to
do this as we can get the nw_info directly from the instance's info cache.

Change-Id: I2bcc2f15b1e5bb52d972098c7bc3e12f160b6feb
Closes-bug: 1294914
(cherry picked from commit 982850f0e912e1a72e501e456cb2b5ef94124ca6)
Merge "Remove unnecessary call to fetch info_cache" into stable/icehouse
Merge "remove unneeded call to network_api on rebuild_instance" into stable/icehouse
Merge "Remove unneeded call to fetch network info on shutdown" into stable/icehouse