LU-13522 mdt: count mdt_mds_mds_conns upon reconnect

LU-13522 mdt: count mdt_mds_mds_conns upon reconnect

mdt.mdt_mds_mds_conns is inter-MDT connection count, it should be
increased upon reconnect (MDT stop and start).

Update sanityn 33c.

Signed-off-by: Lai Siyao <lai.siyao@whamcloud.com>
Change-Id: Ic0dabee10431f39665cb2bc4fa8a014fc78fbd60
Reviewed-on: https://review.whamcloud.com/38512
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Hongchao Zhang <hongchao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>