LU-4349 target: count disconnected exports as stale

LU-4349 target: count disconnected exports as stale

If export is disconnected during recovery then stale client
counter need to be increased.

Test-Parameters: envdefinitions=SLOW=yes testlist=conf-sanity,conf-sanity,conf-sanity,conf-sanity,conf-sanity
Signed-off-by: Mikhail Pershin <mike.pershin@intel.com>
Change-Id: Id4f2a668dbe8d5cd2fa3d392b7df7b4d67a4265a
Reviewed-on: http://review.whamcloud.com/8785
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: wangdi <di.wang@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>