https://review.openstack.org/#/c/171299/ introduces a wrapper for utils.spawn_n
to update context in thread local store. However, there are other routines in
driver code which calls greenthread.spawn or greenthread.spawn_n, so that they
will not update context in thread local store. The commit adds utils.spawn as a
new wrapper, and also make those codes call spawn/spawn_n of utils, in order to
ensure the context of logging is correct.
Change-Id: I3623e60c49e442e2431cf017540422aa59bc285a
Related-Bug: 1404268