The account reaper is using a unique timestamp when deleting
replicas of the same resource. This will result in unnecessary
replication traffic after reaping.
This patch makes the reaper use a single timestamp per resource.
Probe test is modified to check that delete times are equal
across replicas before replicators run.
test_direct_client.py is modified to check that it uses explicit
timestamp when passed to direct_delete_[object|container]
methods.
Drive-by bug fixes in the probe test e.g. it was not sending
X-Backend-Storage-Policy-Index when doing a direct GET to check
object state, so the 404s being verified could in fact be due
to diskfile not existing rather than diskfile being deleted.
Closes-Bug: 1442879
Change-Id: I8bab22d66308bb9d3294e1e0def017c784228423