LU-5075 test: keep LFSCK fail_loc until recovery completed

LU-5075 test: keep LFSCK fail_loc until recovery completed

In sanity-lfsck test_8, the old script may over wrote the fail_loc
before the recovery completed, that will cause the paused LFSCK to
be restarted automatically, then the subsequent manual command for
starting the LFSCK will get -EALREADY. That is unexpected.

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: I8500ecdccf354e83ec70be8dea88943cafa47d81
Reviewed-on: http://review.whamcloud.com/11288
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>