tests: fix HostStatsThread tests

In commit 4567f368bc3b initial tests for HostStatsThread
were added. Unfortunately, the patch was verified
on branch, not on master, so master branch broke
when the patch got merged.

The mistake slipped into because
* the parent patch contained the code which made the
  test work ok, and was abandoned (see below).
* 4567f368bc3b applied cleanly against mastr.

This followup patch fixes that in the following way
- mark test as broken: the existing behaviour is *not*
  to continue in presence of errors - see
  http://gerrit.ovirt.org/#/c/29401/ abandoned
  for that reason.
- wrap a real HostSample to be more correct
- add a timeout to avoid hang indefinitely.

Change-Id: Iefeacf5f105384040b4a81f9835faa1fa5033c07
Signed-off-by: Francesco Romani <fromani@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/35764
Reviewed-by: Dan Kenigsberg <danken@redhat.com>