LU-7649 mgs: skip single OST conf update

LU-7649 mgs: skip single OST conf update

If some OST is marked to regenerate its configuration by
"tunefs.lustre --writeconf", the newly added OSC entry for
this OST should be marked as "skip" just as the new OSP entry
in MDT(LOD) configuration.

Change-Id: I1f680cb81a4c77fcf48ab2df441c821db5d456b5
Signed-off-by: Hongchao Zhang <hongchao.zhang@intel.com>
Reviewed-on: http://review.whamcloud.com/17924
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>