LU-2547 tests: EXCEPT recovery-small/24a for ZFS

LU-2547 tests: EXCEPT recovery-small/24a for ZFS

EXCEPT this test for ZFS as it is failing over 50% of the time
currently.  Re-enable when root cause of failure is located.

Signed-off-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Change-Id: I6c02a4db5a0d9f876cb4e8cff4e614eb3ac86dfd
Reviewed-on: http://review.whamcloud.com/6119
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Hudson
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>