Refactor audit shard tests
Refactor audit shard tests

The existing tests cover a lot of behaviors and carry around a lot of
state that makes them hard to extend in a descriptive mannor to cover
new or changed behaviors.

Change-Id: Ie52932d8d4a66b11c295d5568aa3a60895b84f3b

swiftstack/swift,openstack/swift,swiftstack/swift,tipabu/swift,openstack/swift,openstack/swift,swiftstack/swift,tipabu/swift,openstack/swift,tipabu/swift,tipabu/swift