critwall, fenwick, tantar: improve log output at info level

[pdowler]

Current log output does not really tell the operator what's going on and that the application is working correctly.

issues to consider:

• human readable vs machine readable?
• mixture where events are machine-readable but some human-readable logging provides context

[pdowler]

fenwick appears to have no logging of StorageSite, DeletedArtifactEvent, or DeletedStorageLocationEvent processing at info level... one line per Artifact sync'ed is good.