LU-6000 tests: avoid test failure on b2_4 server

LU-6000 tests: avoid test failure on b2_4 server

The injection failure stub OBD_FAIL_FID_LOOKUP on old MDT
(version < 2.5.4) will cause sanity-lfsck test_4 failure
when traversal the directory. Since we will not land more
patch on b2_4, then skip related test(s) in new version
test scripts.

Test-Parameters: alwaysuploadlogs ossjob=lustre-b2_4 mdsjob=lustre-b2_4 ossbuildno=73 mdsbuildno=73 testlist=sanity-lfsck
Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: I9866707a336865e7e30ba587bd9847c1dae7ea58
Reviewed-on: http://review.whamcloud.com/13000
Tested-by: Jenkins
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Emoly Liu <emoly.liu@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>