LU-6419 fld: fld client lookup should retry

LU-6419 fld: fld client lookup should retry

If FLD client lookup fails because of the remote target
is shutdown (or deactive), it should retry another target,
otherwise it will cause the application failure.

And FLD client should stop retry if the import has
been deactive.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: Ic5934054bf0aff3158b6fe040fcb26699336f038
Reviewed-on: http://review.whamcloud.com/14313
Tested-by: Jenkins
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>