test: check for any stat change
test: check for any stat change

The memstore doesn't seem to refresh kb_used, so we wait for anything to
change. It looks like num_objects changes for memstore.

Signed-off-by: Noah Watkins <86ecd7d1c53cf33a85014f7cab78876cb4491020@gmail.com>

noahdesu/go-ceph,AcalephStorage/go-ceph,theanalyst/go-ceph,ceph/go-ceph,AcalephStorage/go-ceph,webfd/go-ceph,theanalyst/go-ceph,noahdesu/go-ceph,ceph/go-ceph,ceph/go-ceph,webfd/go-ceph