ceph: fix ceph tests and temporarily disable mocks

This fixes some of the Ceph tests, and disables the tests that use
mocking.

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
Reconcile branches wip-ceph vs cluster-stats

- Removing use of 2.7-only subprocess.check_call
- Using 'perf schema' for perf counter output