Refactor auditors to rely on expected gen names

Refactor the various auditors to rely on the audit_location_generator
yielding tuples containing paths with the expected suffix.

We also fix the exception handling for container_sync to not expect a
broker object (since the act of creating a broker object can raise an
exception).

For the object auditor we removed an unneeded check for disk_file
since get_data_file_size() will raise DiskFileNotExist under the same
condition (raises code coverage slightly).

Change-Id: I11d405e629063177ef21543b75e9076da1a03b61
Merge "Refactor auditors to rely on expected gen names"