Remove log_handler module from oslo-incubator sync

log_handler is now part of
oslo.messaging(I9ea051ec7e3614579341a31d8dc1c13d9514b8a9).

Change-Id: Ic3493b8717c83285e6aafeae23a29d2794a9b2a9
Merge "Remove log_handler module from oslo-incubator sync"