Do not monkey patch eventlet in unit tests

Unit tests are sufficiently focused that eventlet monkey-patching
should not be required. Here it is turned off.

Change-Id: Ib3c346cccaada054e53e903fbfe80be45b9649ad

nova/tests/unit/__init__.py

@@ -22,16 +22,8 @@
    :platform: Unix
 """
 
-import eventlet
-
 from nova import objects
 
-eventlet.monkey_patch(os=False)
-
-# NOTE(alaski): Make sure this is done after eventlet monkey patching otherwise
-# the threading.local() store used in oslo_messaging will be initialized to
-# threadlocal storage rather than greenthread local.  This will cause context
-# sets and deletes in that storage to clobber each other.
 # NOTE(comstud): Make sure we have all of the objects loaded. We do this
 # at module import time, because we may be using mock decorators in our
 # tests that run at import time.