Reset the _TRAITS_SYNCED global in Traits tests
Reset the _TRAITS_SYNCED global in Traits tests

The global is reset before and after tests because we don't know
what other tests might have been messing with it (without even
knowing) in this process. We want to start from a clean slate and
leave the slate clean.

Change-Id: I42b9a7973ec5c4f42578779dc6ad59274212113f
Closes-Bug: #1696267

klmitch/nova,gooddata/openstack-nova,gooddata/openstack-nova,mikalstill/nova,jianghuaw/nova,gooddata/openstack-nova,jianghuaw/nova,Juniper/nova,klmitch/nova,klmitch/nova,klmitch/nova,vmturbo/nova,vmturbo/nova,openstack/nova,rahulunair/nova,mikalstill/nova,mahak/nova,mikalstill/nova,mahak/nova,vmturbo/nova,Juniper/nova,jianghuaw/nova,rahulunair/nova,rahulunair/nova,jianghuaw/nova,vmturbo/nova,openstack/nova,openstack/nova,phenoxim/nova,gooddata/openstack-nova,Juniper/nova,Juniper/nova,phenoxim/nova,mahak/nova