This change implements the ranged loop observer to replace the audit
chore that builds the audit queue.
The strategy employed by this change is to use a collector for each
segment range to build separate per-node segment reservoirs that are
then merge them during the join step.
In previous observer migrations, there were only a handful of tests so
the strategy was to duplicate them. In this package, there are dozens
of tests that utilize the chore. To reduce code churn and maintenance
burden until the chore is removed, this change introduces a helper that
runs tests under both the chore and observer, providing a pair of
functions that can be used to pause or run the queueing function.
https://github.com/storj/storj/issues/5232
Change-Id: I8bb4b4e55cf98b1aac9f26307e3a9a355cb3f506
590d44301c