Enhance unit tests for batched sequence allocation

The enhanced sequence allocation in CBG-258 means that sequences allocated to documents in our unit tests may be non-deterministic when the tests are run under race.  Currently this is being handled by enforcing sequence allocation batch sizes of 1 in most unit tests.

To provide better coverage of the sequence allocation changes, it would be preferable to refactor the existing tests to not rely on specific sequence values.  This includes both tests that are asserting specific sequence values in the rests, as well as tests that use waitForSequence to manage timing.