Makes the backup tests less onerous

The backups test code was looking for an exact number of elements to
be returned from the backups list calls. This made running the tests
kind of a pain, so this commit counts the number of backups before a
backup is created and uses this for the later assertions.

Change-Id: I186c9e04a91e86fca612078415413468757297ca
Merge "Makes the backup tests less onerous"