To tell when replication for a device has finished, it's important to
know when the replicator is removing objects. This was previously
handled for the object-replicator
(object-replicator.partition.delete.count.<device> and
object-replicator.partition.update.count.<device> metrics) but not the
account and container replicators.
This patch extends the existing DB removal count metrics to make them
per-device. The new metrics are:
account-replicator.removes.<device>
container-replicator.removes.<device>
There's also a bonus refactoring and increased test coverage of the DB
replicator code.
Change-Id: I2067317d4a5f8ad2a496834147954bdcdfc541c1
66400b7337