Stub out rpc notifications in ec2 cloud unit tests

The ec2 cloud unit tests are running through the compute
manager and if something fails and is wrapped with the
wrap_exception decorator, we can get big ugly stack traces
in the log. We should be using the fake_notifier in these
tests like we do in the nova.tests.compute.test_compute
setup.

This also changes the test_ec2_validate test to use
local conductor like the other cloud tests that are going
through conductor.

Change-Id: I59bed0903aeef4086872c10d93a06f34b072dce3
Partial-Bug: #1348661
Merge "Stub out rpc notifications in ec2 cloud unit tests"