This structure is entirely unused within the audit module, and is only
used by repair code. Accordingly, this change moves the structure from
audit code to repair code.
Also, we take the opportunity here to rename the structure to something
less generic.
Refs: https://github.com/storj/storj/issues/4669
Change-Id: If85b37e08620cda1fde2afe98206293e02b5c36e