Branch:b_new_cmd

Branch:b_new_cmd
Disable target_stop_recovery_thread temporarily, because it
might cause dead-lock of target_recovery_thread. For example
1) in recovery, if clients are still not reconnected to the MDS.
2) this MDS failed again, try to stop_recovery_thread here.  obd_abort_recovery is set to 1.
3) MDS disconnect stale exports, obd_abort_recovery will be reset to 0. and check the next
   replay, but currently the MDS already disconnect the exports. and next replay req will
   never reached.  so the recovery-thread will hang there.