Fix bug 1129760
Without speed limit, DB auditor will likely consume high CPU% on
storage node. That will highly impact the cluster's performance.
This patch adds two options for account/container auditor:
- containers_per_second: Maximum containers audited per second
- accounts_per_second: Maximum accounts audited per second
DocImpact
Change-Id: I9faa506438185a83ca77db4906969328624d015f