This test has multiple assumptions that do not hold for WB/WO:
1. it assumes primary storage errors would propagate to user I/O
2. cache is stopped with metadata flush, which would fail
3. after stopping CAS core content is verified with fio
4. cache is so small that it overfills, resulting in PT I/O further
complicating error accounting.
Signed-off-by: Rutkowski, Adam J <adam.j.rutkowski@intel.com>