Log if a quota_usages sync updates usage information

There's some periodic quota_usages syncing that can occur to help
correct any drift that may happen.  It would be useful to log when that
occurs as it may indicate an issue somewhere.

Change-Id: I5b90ab42059ae8ebd0c3890accafb98e70ed037e
Merge "Log if a quota_usages sync updates usage information"